Gradually, enlarging 4 × 4 cm, well-circumscribed, mobile scalp nodule over the left parietal area in a 38-year-old man, noted after hitting a towel rack 7 months ago. Papanicolaou stained fine-needle aspiration smears stained showed groups of basaloid cells and eosinophilic shadows (ghost cells) with focal foreign body giant cells [Figure 1].

1. What is the most likely diagnosis?

Pilomatricoma

Answer: a

Option a: Pilomatricoma showed cellular aspirates comprised of micro-fragments containing groups of basaloid cells without peripheral palisading. The basaloid cells showed high nuclear: cytoplasmic ratio, evenly dispersed chromatin with a few cells showing prominent nucleoli. Clumps of refractile keratin and multinucleated giant cells were also seen in the background. These tumors can have mitosis and, hence, could be misinterpreted as carcinomas. Even thought, it may be difficult to evaluate in fine-needle aspiration (FNA) aspirate, ghost cells (a.k.a. eosinophilic shadow cells), which have no nuclear staining, are clues to correct diagnosis.

Option b: Melanoma may present as asymmetrical and gradually enlarging lesion with irregular borders. However, this lesion is symmetrical with well-defined borders and uniform tan color. Desmoplastic melanoma is usually present on the head-and-neck region and can appear as erythematous, pink or pale nodules or plaque.^[1] Histologically, melanoma can mimic features of other tumors such as neuroendocrine tumors, poorly differentiated carcinoma, and lymphoma.^[2] A typical case of melanoma shows high nuclear to cytoplasmic ratio with a prominent cherry red nucleoli and hyperchromatic nuclei with irregular nuclear membrane.^[2] Immunohistochemistry is widely used in melanoma to differentiate it from other tumors. S-100 is commonly used and has good sensitivity.^[2] Other markers have good specificity such as Melan-A, tyrosinase, or HMB45.^[2]

Option c: Merkel cell carcinoma (MCC) often appears as asymptomatic red, pink, or blue papules or nodules and lacks distinctive clinical features. Histopathologically, it is marked by round nuclei with finely granular chromatin, inconspicuous nucleoli, scant cytoplasm, and nuclear crush artifacts, along with multiple mitotic figures and apoptotic bodies resembling small cell carcinoma.^[3] MCC shows high sensitivity to cytokeratin 20 and neurofilaments, whereas negative staining for thyroid transcription factor 1 and cytokeratin 7 helps distinguish it from small cell carcinoma.^[3]

Option d: Squamous cell carcinoma (SCC) usually presents as a red scaly plaque. SCC can be classified with various degrees of differentiation from well to poorly differentiated. SCC can be classified into many subtypes and histopathologic features include atypical squamous cells, keratin pearls, and sometimes hyperkeratosis.^[4] Well-differentiated tumors exhibit interconnecting follicular infundibular type squamous epithelium.^[4] SCC is characterized by atypical squamous cells, whereas pilomatricoma consists of basaloid cells and shadow cells. In addition, immunohistochemistry is not typically used except in the cases of poorly differentiated SCC.^[4] Cutaneous SCC stains positive with p63, p40, MUC1 (epithelial membrane antigen), CK5/6, MNF116, and high-molecular weight 34 E12. BerEp4 should be negative in SCC.^[5]

Option e: Proliferating trichilemmal tumor is a tumor originating from the outer root sheath of a hair follicle.^[6] The fine-needle aspirates are usually cellular and show syncitial sheets of squamous epithelial cells, amorphous material, keratin, and clusters of small cells with hyperchromatic nuclei mostly basaloid cells.^[6] This lesion does not show ghost cells, calcification, cholesterol clefts, and foreign body giant cells.^[6]

The lesion showed [Figure 2a-d] two types of cells: Basaloid cells and shadow cells. Basaloid cells are present along the periphery in variable proportion. They are small, monotonous with scant cytoplasm with indistinct cellular borders and evenly distributed chromatin. Basaloid cells merge gradually or abruptly with so-called ghost or shadow cells. Ghost cells have abundant pink cytoplasm and open space at their center. Focally, the periphery of the lesion showed foreign body giant cell reaction.

The excisional biopsy showed an intradermal, fairly well-circumscribed lesion measuring 4 × 4 × 4 cm. Microscopic images are shown in Figure 3.

2. How does the expression of beta-catenin and p63 in pilomatricoma differ in intensity and distribution from other hair matrix tumors?

Pilomatricoma exhibits nuclear beta-catenin and nuclear p63

Answer: a

a) Pilomatricoma exhibits nuclear beta-catenin and nuclear p63 Explanation: The expression and distribution of certain proteins, such as beta-catenin and p63, can be used to differentiate pilomatricomas from other types of hair matrix tumors. Beta-catenin was positive in the basaloid cell population, showing both cytoplasmic and nuclear staining.^[7,8] Nuclear localization is particularly characteristic of pilomatricoma and can help distinguish it from other skin tumors, where beta-catenin is usually restricted to the membrane.^[8] p63 is a marker that is often used to identify squamous epithelium and squamous differentiation.^[8] In pilomatricoma, p63 typically shows strong positivity in the basaloid cells surrounding the ghost cells, reflecting the squamous nature of the tumor.^[7]

3. What is the recommended treatment approach for pilomatricoma?

Surgical excision with clear margins

Answer: a

a) Surgical excision with clear margins. Because it is a benign tumor, complete removal with clear margins is usually curative and prevents recurrence.^[9]

Pilomatricoma (also known as pilomatrixoma and calcifying epithelioma of Malherbe) is a benign tumor of hair follicle matrix that most frequently develops with bimodal age distribution of first and sixth decade.^[9] Pilomatricoma usually presents as a firm nodule with the overlying skin appearing normal but can present with blue-red discoloration.^[9] The tumor can occasionally have keratotic appearance, imitating squamous cell carcinoma, or can present with telangiectasia resembling basal cell carcinoma (BCC).^[9] Although malignancy is rare, pilomatricoma can progress into pilomatrix carcinoma.^[10] Pilomatricoma is commonly seen in the head-and-neck area.^[10] Involvement of palms and soles or genitalia has not been reported.^[10] Surgical excision with clear margins is the recommended treatment.^[10] Following total resection, recurrence is uncommon.^[10]

The histological appearance of a pilomatricoma is solid and nests of basaloid cells. This is different from other types of hair matrix tumors which typically have peripheral palisading. The presence of ghost cells, which are tiny, pale cells that seem “ghostly” under the microscope, is a crucial diagnostic clue of pilomatricomas. They arise when the cytoplasm of maturing cells is replaced by keratin, a protein found in the epidermis, or outermost layer of the skin.^[11] Beta-catenin in pilomatricoma often shows both nuclear and cytoplasmic accumulation and p63 typically demonstrates strong nuclear positivity in the basaloid cells surrounding the ghost cells.^[7,8] The nuclear distribution of both beta-catenin and p63 is a distinguishing feature from other hair matrix tumors, where they may show a predominantly membranous pattern of beta-catenin and variable P63.

Pilomatricomas are commonly misdiagnosed and are rarely considered as part of the differential diagnosis due to multiple overlapping cytologic features as shown in Figure 4. Clinical differential diagnosis includes but is not limited to BCC which lacks shadow cells and frequently has a mucinous stroma. BCC has many subtypes and are characterized as high-risk and low-risk histologic subtypes. Nodular BCC is the most common and falls under low-risk subtypes.^[12] Nodular BCC can appear as a pearly, translucent papule or nodule with telangiectasia and histopathology usually show basaloid keratinocytes with peripheral palisading and clefting.^[12,13] Micronodular, infiltrative, sclerosing, and morpheaform are considered higher-risk subtypes and more likely to recur than low-risk histologic subtypes which include superficial and nodular BCC.^[13]

Trichilemmal cysts (TCs) are benign cystic lesions originating from follicular isthmus epithelium and can present similar to pilomatricoma with slow-growing, asymptomatic, and firm nodules in the scalp.^[14] However, histologically TC found to have squamoid cells with abundant eosinophilic cytoplasm, compared to basaloid small cells in pilomatricoma.

Epidermal inclusion cyst was considered on the differential and usually occurs on the scalp, neck, back, and extremities.^[15] However, it is less likely given absence of central punctum on examination. Lipoma is a benign adipose tumors and can present similar to pilomatricoma but less likely since FNA did not visualize adipose tissue cells.^[16]

MCCs do not have distinctive clinical features and can present as asymptomatic red or pink or blue papules or nodules.^[3] Histopathologic features include round nuclei with finely granular chromatin, inconspicuous nucleoli, scant cytoplasm, showing molding, and crush artifact.^[3] The high nucleus: cytoplasm ratio gives it a blue or basaloid appearance (3). In addition, immunostains have good sensitivity and can further confirm the diagnosis of MCC which includes cytokeratin 20, low-molecular-weight cytokeratins (e.g., CAM5.2), and neurofilaments.^[3] Electron microscopy shows paranuclear and/or cytoplasmic bundles of tonofilaments (keratin intermediate filaments), cytoplasmic dense-core granules, and desmosomal attachments.^[3] FNA of MCC typicall show small, round, or oval cells with round-to-oval nuclei and scant cytoplasm. Nuclei have fine chromatin and small, inconspicuous nucleoli. Occasional nuclear moldingcan be observed.^[17]MCC is less lik ely because histopathology lacks shadow cells. Table 1^[3,4,13-18] shows the differential diagnosis for pilomatricoma.

Rare pilomatrixoma can be elusive if not kept in the differential of basaloid neoplasms in fine needle aspiration of subcutaneous head-and-neck lesions. FNA from pilomatrixoma can be cellular with cells showing high nuclear to cytoplasmic ratio, prominent nuclei, and mitotic figures. Clumps of refractile keratin and “ghost cells” are major clues to appropriate diagnosis. Atypical basaloid cells and mitotic figures may lead to a diagnostic pitfall to report this entity as a malignancy. Ghost cells are important for the cytological diagnosis of pilomatricoma.

All data generated or analyzed during this study are included in this published article. No additional datasets were generated or analyzed during the current study. Therefore, data sharing is not applicable to this article as all necessary information is provided within.

FNAC – Fine-needle aspiration cytology.

CB, SA, MYAK and VBS: Made substantial contributions to the conception and design of the work, led the initial drafting of the manuscript, and was primarily responsible for its overall structure and content; CB and SA: Significantly contributed to the study design and data analysis; MYAK: Provided critical insights into the methodology and interpretation of results; VBS: Offered expert guidance on the clinical implications and supervised the project.

All authors critically reviewed and revised the manuscript to ensure its intellectual content and integrity, and have given final approval of the version to be published. They all agree to be accountable for all aspects of the work.

A 60-year-old woman with a left neck mass was referred for an ultrasound-guided fine needle aspiration (FNA). Ultrasound examination revealed a 2.7 × 2.2 × 1.2 cm, well-circumscribed, solid, hypoechoic lesion with smooth sharp borders in the right neck at level 2A. During the physical examination and interview, the patient reported to have an undiagnosed palate mass. The left neck mass was targeted for FNA. The Diff-Quik stain of the smear showed clusters of papillary-like epithelioid cells with round-to-oval nuclei with wrinkled membranes and extracellular metachromatic stromal fragments. The Papanicolaou stain showed cells with nuclear grooves, small nucleoli, and fine vesicular chromatin. The cells had a moderate amount of delicate cytoplasm, focally intermingled with scant stromal components. The cell block also showed clusters of papillary structures with a cribriform-like architecture [Figure 1a-d].

Q1. What is the most likely diagnosis?

Papillary thyroid carcinoma

Answer: C

Slightly irregular nuclei with grooves similar to those seen in papillary carcinoma of the thyroid gland are present; however, intranuclear inclusions are absent. The cytological findings combined with clinical information regarding the presence of a mass in the palate are most consistent with metastatic PAC. Pleomorphic adenoma, basal cell adenoma, and myoepithelioma are benign tumors and do not metastasize to the neck lymph nodes.^[1]

Q2. Which immunohistochemical panel and findings would be best to confirm the diagnosis of PAC?

Thyroid transcription factor-1 (TTF-1) positive, S100 positive, cytokeratin-7 (CK-7) positive

Answer: B

Immunohistochemistry panel was performed on the cell block which revealed these cells to be positive for CK-7, S100, and Sry-related HMg-Box 10 (SOX10) gene and negative for p40, p63, smooth muscle actin, TTF-1, thyroglobulin, and PAX8 [Figure 2]. Negative TTF-1, thyroglobulin, and PAX8 ruled out metastatic papillary thyroid carcinoma. In the setting of the patient’s palate mass, PAC was considered in this FNA.

PAC is immunoreactive for CKs including CK7, in 100% of cases and S100 protein 97–100%. p63 is positive in 78–100% of cases, whereas p40 is usually negative.^[1] SOX10 is positive in 86% of PACs.^[2]

There is some degree of overlap in the immunohistochemical profile of secretory carcinoma of the salivary glands and PACs. Secretory carcinomas are positive for CK7, S100, SOX10, vimentin, and mammaglobin, and negative for p63, p40, NR4A3, and discovered on GIST-1.^[1] However, the cytomorphology of secretory carcinomas varies in that they are composed of microcystic/solid, tubular, and papillary-cystic structures with luminal secretions. The tumor cells in secretory carcinomas have vacuolated pink cytoplasm and granular chromatin.^[1]

Q3. Which one of the following is correct about PAC?

PAC is the most common intraoral salivary gland tumor

Answer: C.

PAC is the second most common intraoral salivary gland carcinoma, which rarely metastasizes to the neck lymph nodes. Pleomorphic adenoma is the most common benign tumor and mucoepidermoid carcinoma is the most common malignant tumor of the minor salivary glands of the oral cavity.^[3] The palate is the most common site for PAC and the overall prognosis of PAC is excellent with a 10-year survival rate of 94–99%.^[1] The main malignant salivary gland tumors that can metastasize to the neck lymph nodes are mucoepidermoid carcinoma, adenoid cystic carcinoma, acinic cell carcinoma, secretory carcinoma, salivary duct carcinoma, myoepithelial carcinoma, epithelial-myoepithelial carcinoma, hyalinizing clear cell carcinoma, carcinoma ex pleomorphic adenoma, and lymphoepithelial carcinoma.^[4]

Q4. What chromosomal abnormality or molecular findings are seen in PAC?

ETS Variant Transcription Factor 6 (ETV6)-Neurotrophic Tyrosine Kinase Receptor Type 3 (NTRK3) fusion

Answer: D.

Most cases of secretory carcinomas show chromosomal translocation, t (12; 15) (p13; q25) resulting in an ETV6-NTRK3 fusion. Adenoid cystic carcinomas have (6;9) or t (8;9) translocations, resulting in MYB-NFIB and MYBL1-NFIB fusions. Mutations in TP53 (55%), HRAS (23%), and PIK3CA (23%) are seen in salivary duct carcinoma. Conventional PAC has predominantly PRKD1 mutation and cribriform subtype has PRKD1,2,3 fusions. Cribriform subtypes are more likely metastasize to the neck lymph nodes.^[1,5]

The patient underwent a right maxillectomy with ipsilateral neck dissection 5 months after the FNA procedure, which showed a 5.3 cm high-grade PAC with metastasis to the two lymph nodes. Microscopic examination of the specimen revealed an infiltrative tumor with papillary structures, fibrous connective tissue stroma, and open chromatin nuclei [Figure 3a-c].

PAC of the minor salivary glands is a rare head-and-neck cancer, which generally has a good prognosis. PACs were previously known as “polymorphous low-grade adenocarcinoma”. The recent World Health Organization classification of head-and-neck tumors has characterized it as PAC.^[1,6]

There are two subtypes of this tumor, conventional subtype and cribriform subtype. The conventional subtype shows various patterns, including tubules, trabeculae, and microcysts with a mucoid/myxoid background. The cribriform subtype shows papillary structures and glomeruloid bodies in a fibrous stroma. Their nuclei show open chromatin.^[1] Recognizing PAC can be challenging due to diverse architectural patterns.^[1]

Due to the intraoral location of PAC and rare occasions of metastasizing to the neck lymph nodes, these tumors are hardly sampled by FNA, and therefore, cytopathologists have less experience with the diverse cytomorphology of PAC.^[7]

Overall, cytology smears show uniform moderately sized cells with relatively scant cytoplasm and round-to-oval nuclei, forming papillary, tubular, and irregular solid clusters. Dense globular or fibrillary stroma can be seen. Therefore, PAC can resemble adenoid cystic carcinoma or epithelial-rich pleomorphic adenoma. Occasional nuclear grooves and pale chromatin are also seen in PAC and can be misinterpreted as papillary thyroid carcinoma.^[1,7]

In our case, TTF-1 and thyroglobulin stains were performed to rule out metastatic papillary thyroid carcinoma.

PAC is immunoreactive for CKs and S100 protein. Staining for p63 is variable. p40 is typically negative. Other positive immunomarkers include mammaglobin (67–100%), CD117 (60%), carcinoembryonic antigen (54%), glial fibrillary acidic protein (15%), melanoma-specific antigen (13%), and epithelial membrane antigen (12%).^[1]

Pleomorphic adenomas are immunoreactive with pleomorphic adenoma gene 1 and human high-mobility group protein A2. Cytologically, most of the time, pleomorphic adenomas show the characteristic fibrillary matrix, mixed with myoepithelial cells which merge into the epithelial component. The chromatin of the tumor cells is dark unlike PAC.^[1]

Adenoid cystic carcinomas are basaloid tumors. The smears show cohesive clusters of cells forming sheets or show tubular, complex, or cribriform architecture containing hyaline globules. The tumor cells have hyperchromatic nuclei.^[1]

Other differential diagnosis includes cribriform-morular thyroid carcinoma (CMTC) which is now considered a distinct malignant thyroid neoplasm. The smears of CMTCs are hypercellular showing papillary and cribriform clusters with slit-like spaces and swirling of nuclei, representing morulae. Nuclei can show peculiar nuclear clearing with thick membranes, grooves, and pseudoinclusions.^[8]

Genetic alterations in PRKD 1/2/3 genes have been described in PACs and may be useful in distinguishing PAC from other salivary gland neoplasms.^[5]

In summary, the cytologic features of PAC overlap with other salivary gland neoplasms and papillary thyroid carcinoma. In our case, the immunohistochemical stains in addition to cytomorphology (pale chromatin and papillary-like structures) with the clinical information helped us reach a diagnosis of FNA.

FNA – Fine needle aspiration

PAC – Polymorphous adenocarcinoma.

What is the most likely diagnosis?

Secretory carcinoma

c. Apocrine carcinoma

The patient presented with features of invasive carcinoma of the breast and with skin ulceration. Fine needle Aspiration cytology (FNAC) smears predominantly showed cells with abundant vacuolated cytoplasm [Figure 1]. Biopsy showed two populations of cells with well-defined cytoplasmic borders; one with abundant eosinophilic cytoplasm with PAS-positive diastase-resistant granules, and the other with abundant vacuolated cytoplasm. The cells showed nuclear atypia, brisk mitotic activity, and atypical mitosis [Figure 2]. Two types of cells are seen in apocrine carcinoma. Type A cells have abundant eosinophilic granular cytoplasm, enlarged nuclei and the prominent nucleoli, and type B cells have abundant vacuolated cytoplasm with intracytoplasmic lipids. The type A cells are diastase-resistant and, the PAS-positive.^[1-7]

The diagnostic interpretation of apocrine carcinoma on cytology smears may be challenging due to its morphologic mimics. FNAC smears show large polygonal cells with abundant granular cytoplasm and sharply defined borders. The nuclei are vesicular, with irregular nuclear bor ders, and show prominent nucleoli.^[8] Predominance of type B cells in cytology smears poses difficulty in arriving at the diagnosis. This might be due to sampling error. In 2005, Japaze et al.,^[6] proposed the following criteria for diagnosing apocrine carcinoma: (i) 75% of tumor cells exhibiting apocrine features, (ii) large cells with granular eosinophilic cytoplasm, (iii) sharply defined cell borders, (iv) large, round, vesicular, may be the pleomorphic nucleus, and (v) low N: C ratio (≤1:2).^[6]

Which of the following immunohistochemical marker is generally negative in apocrine carcinoma of breast?

ER

a. ER

Apocrine carcinomas lack ER and PRs, Bcl-2, but have AR and express gross cystic disease fluid protein-15 (GCDFP-15), GATA binding protein 3, CK7, CK8, CK18, CK19, CK20, expression of MUC1 (EMA), and E-Cadherin. HER2/neu may or may not be positive. Basal cytokeratins such as CK5/6, CK14, CK17, and p63 are variably positive. GCDFP is present in the breast cysts and in apocrine cells of mammary glands, salivary glands, sweat glands, Paget disease, etc. HER2/neu is positive in 30–60% of carcinomas with apocrine differentiation. GCDFP-15 and AR are considered the hallmarks of apocrine differentiation [Figure 3]. The expression of GCDFP-15 appears to be reduced in advanced apocrine carcinoma. In oncocytic carcinoma , ER, PR, and anti-mitochondrial antibodies are positive and AR and GCDFP-15 are negative.^[1-15] Hence, apocrine carcinomas have two molecular subtypes: Triple-negative and HER2-positive.^[10]

To be designated as “Carcinoma with apocrine differentiation,” _________% of the tumor cells should have distinct apocrine morphology.

50%

d. 90%

To be designated as “Carcinoma with apocrine differentiation,” the distinct apocrine morphology should be evident in >90% of the cancer cells. Previously, the cutoff percentage of tumor cells had been defined as 75% by Japaze et al., to be diagnosed as apocrine carcinoma ^[1-4,9-12]

Is apocrine carcinoma associated with BRCA 1 or 2?

Yes

b. No

Although loss of PTEN (Phosphatase and tensin homolog) function may indicate familial breast carcinoma, there is no association between apocrine carcinoma and BRCA1 or BRCA2.^[5]

Which of the following breast carcinomas has a worse prognosis?

Triple-negative invasive breast carcinoma of no special type

a. Triple-negative invasive duct carcinoma of no special type

The triple-negative subtype of apocrine carcinoma of the breast has better prognosis than triple-negative invasive breast carcinoma of no special type (NST), as targeted therapy with drugs used in prostate carcinoma such as fluoxymesterone that inhibits androgen signaling, is available.^[1-6,11] The other two subtypes carry better prognosis.

Invasive carcinoma of breast with apocrine differentiation is a special subtype of breast carcinoma.^[16] The age of presentation ranges from 48 to 60 years.^[1] It is uncommon and the incidence ranges from 0.3% to 4% of female invasive breast carcinomas. It is seen more commonly in middle-aged women. Its incidence is extremely rare in male breasts. It is an aggressive malignancy. It can be misdiagnosed as invasive duct carcinoma. Lymph node metastasis has been reported in apocrine carcinomas. Malignant adnexal tumors of the skin may arise from apocrine, eccrine, sebaceous, ceruminous, and sweat glands. Normal breast ductal cells undergo metaplasia and transform into apocrine cells. The pattern of growth of apocrine carcinoma is like that of invasive duct carcinoma.^[1-6,8-12]

Apocrine carcinoma was first described by Krompecher et al. in 1916. However, the histologic criteria to diagnose the apocrine carcinomas were defined by Japaze et al.^[3,6]

The 5^th edition of the World Health Organization (WHO) Classification of Breast Tumors recognized “Carcinoma with apocrine differentiation” as a distinct entity. Apocrine differentiation occurs in invasive carcinomas NST, lobular, tubular, medullary, and micropapillary carcinomas, DCIS, and lobular carcinoma in situ.^[1,7]

Apocrine carcinoma arises from the milk duct of the breast. Grossly, it presents as a solidified whitish mass. It generally presents with skin ulceration. Nipple discharge may or may not be present. It has been reported in accessory breast also. The growth pattern is like that of invasive duct carcinoma. The cells of apocrine carcinoma have abundant eosinophilic granular cytoplasm, well-defined cytoplasmic borders, apical snouting at places, large round vesicular nuclei, and multiple nucleoli.

Differential diagnoses of carcinoma with apocrine differentiation include malignancies such as secretory carcinoma, oncocytic carcinoma, lipid-rich carcinoma, invasive duct carcinoma, and benign lesions such as granular cell tumor, apocrine metaplasia, and histiocytic proliferation [Figure 4].^[8,17-27] Immunohistochemistry can help in cases where morphological interpretation alone cannot aid in differentiating between these cases [Table 1].^{[1-8,10,17-28]}

Focal apocrine changes can be seen in several breast lesions ranging from benign cysts to invasive carcinomas. Benign breast lesions with apocrine morphology include fibrocystic disease, apocrine cysts, the apocrine adenosis, and apocrine adenoma. Malignant lesions with apocrine morphology include apocrine DCIS and apocrine carcinoma. Hence, diagnosis of apocrine carcinoma can be challenging. Overlapping of cells, nuclear pleomorphism, and high N: C ratio are not usually seen in benign lesions with apocrine differentiation.^[5,8]

Cytogenetic analysis of apocrine carcinoma cells reveals gains of 1p, 1q, 2q, 7 and 17, losses of 1p, 12q, 16q, 17q, and 22q.^[5]

Electron microscopy of the apocrine carcinoma cells shows abundant cytoplasm with well-defined outlines, membrane-bound electron-dense granules in the cytoplasm, abundant Golgi apparatus, mitochondria with incomplete cristae and perinuclear condensation, and empty vesicles. In oncocytic carcinoma, numerous mitochondria are seen occupying >60% of the cytoplasm and they are seen to be dispersed, in contrast to apocrine carcinoma.^[4,8]

In the gene expression studies, these tumors express luminal cytokeratins (AMACR) and lack basal features. Hence, these tumors are called “Luminal Androgen Receptor” (LAR) tumors. A small proportion of cases may show a basal phenotype. AMACR is positive in 97% of invasive carcinomas with apocrine differentiation, the 96% of apocrine DCIS, but only in 22% of carcinomas without apocrine differentiation.^[10]

Next-generation sequencing frequently shows loss of PIK3CA/PTEN/AKT and TP53, followed by mutations of KRAS, NRAS, and BRAF.^[10,13]

Genetic studies on the AR gene showed the highest CAG repeats in DCIS with apocrine differentiation compared to fibroadenomas and invasive breast carcinomas.^[10] Immunohistochemical and molecular features do not necessarily correlate in all cases of carcinomas with apocrine differentiation.^[10]

The expression of PD-L1 is low in apocrine carcinoma. They are found to be microsatellite stable.^[10] Expression of 5a-reductase is found in 60% of apocrine carcinomas, and it correlates with poor prognosis in terms of invasion of lymphatics, blood vessels, and higher histologic grade. Gamma-glutamyl transferase 1 and tumor-associated glycoprotein-72 are specific markers of apocrine differentiation.^[5]

The unavailability of molecular and genetic studies due to financial constraints in the setting of developing countries may pose the challenge in diagnosing apocrine carcinoma.^[3]

Apocrine carcinoma is an aggressive malignancy that tends to ulcerate the skin, and metastasize to lymph nodes. It is of two types – triple-negative and HER2-positive. Even in triple-negative cases, targeted therapy with anti-androgen is available. Hence, making a correct diagnosis of the tumor is necessary. Whenever vacuolated cells are encountered in the cytology smears, especially in an elderly female/male, it is prudent to sample the lesion thoroughly so that making an inappropriate diagnosis can be avoided.

The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request.

AMACR – Alpha-methyl acyl-CoA racemase

GATA3 – GATA binding protein 3

GCDFP 15 – Gross cystic disease fluid protein 15

AR – Androgen receptor

DCIS – Ductal carcinoma in situ

LCIS – Lobular carcinoma in situ

ER – Estrogen receptor

FNAC – Fine-needle aspiration cytology

H & E – Hematoxylin & Eosin

IHC – Immunohistochemistry

LAR – Luminal androgen receptor

MGG – May Grunwald-Giemsa

MRM – Modified radical mastectomy

PR – Progesterone receptor.

A 57-year-old female presented with nausea, vomiting, and headache over a year. The patient had no specific complaints except for gradual weight loss over the past year. Computed tomography scan (CT) was done. T2-weighted sagittal images show an ill-defined T2 hyperintense cystic space occupying a lesion in the occipital lobe. There is ipsilateral compression of the occipital horn of the ventricle and disproportionate perilesional edema with midline shift [Figure 1a]. A craniotomy was performed on the suspicion of a glioma. Intraoperatively, the tumor was yellowish white non-vascular, and soft surrounded by viscous yellow fluid. The bits of tumor tissue sent for squash diagnosis were yellow, firm, and difficult to squash and spread. Rapid hematoxylin and eosin stain was performed.

Definitive sections were sent for histopathology and immunohistochemical staining was done.

What is the diagnosis based on the clinical history, imaging findings, and photomicrographs [Figure 1] provided?

Glioma

1. (c) Metastatic carcinoma

2. (a) CK7, CK20, TTF-1, GATA3, PAX-8, and CDX2

Squash smear cytology is a rapid and reliable method for intraoperative diagnosis of inflammatory and neoplastic brain lesions.^[1]

Squash smears were moderately cellular and showed cohesive clusters and glandular arrangement of tumor cells against a thin mucoid background [Figure 1b-c]. The tumor cells had round to oval hyperchromatic nuclei and a moderate amount of cytoplasm. A focus shows calcification. The findings were suggestive of a non-glial lesion, possibly metastases. Histopathology sections showed well-formed glands and sheets of tumor cells with pools of mucin and psammoma bodies confirming the diagnosis of metastatic adenocarcinoma [Figure 2a-d].

The most common tumors leading to brain metastases include lung and breast followed by renal tumors. In the present case, the tumor cells showed strong immunopositivity for CK7 and were immunonegative for CK20 [Figure 2e and f]. In a female patient, CK7-positive and CK20-negative adenocarcinomas warrant the search for primary in the lung, breast followed by the uterus (endometrial), pancreas, and gallbladder.

3. Which of the following is the most common intracranial tumor?

Gliomas

4. Which of the following is a differential diagnosis of metastases to the brain?

Abscess

3. (b) Metastas es

4. (d) All of the above

The differential diagnosis of metastases to the brain includes primary tumors of the brain, parasites, and abscesses.

Squash cytology smears of glial tumors are cellular with specific cytomorphological features of the tumor cells. For instance, the squash smears of low-grade gliomas show sparse cellularity of tumor cells in a fibrillary background in contrast to high-grade gliomas which are characterized by hypercellularity, endothelial proliferation, necrosis, and mitoses. Necrosis is also often noted in cases of brain abscess, characteristically described as liquefactive necrosis. Fungal, tubercular, and parasitic infestation can also show necrotic background.

Metastases to the brain are a known complication in approximately 20% of malignancies.^[2] Brain metastases are often detected in CT and magnetic resonance imaging scans and previously known cases of malignancy during routine investigations. In most cases, metastases travel through the hematogenous route from lung tumors, breast carcinomas, renal cell carcinomas, and melanomas by breaching the blood–brain barrier.^[3] Metastases are usually noted as intra-axial, intraparenchymal masses with a varied range of radiological differential diagnoses including gliomas, abscesses, and infections. Furthermore, in approximately 15% of cases, a primary tumor is not found.^[4] In the index case, in the absence of any specific complaints elsewhere and a mass lesion in the brain, the suspicion of metastases was unlikely on clinical and radiological examination.

These cases are challenging and the surgeon relies on intraoperative diagnosis for immediate surgical management. In such scenarios, squash cytology can be reliably used to differentiate between metastatic from primary central nervous system neoplasms.

The squash smear cytomorphology depends on the type of primary tumor (adenocarcinoma, small cell carcinomas, melanoma, lymphoma, etc.). An algorithmic approach and workup with immunohistochemical markers can be useful for the detection of the primary tumor.

Immunohistochemical panel for morphologically designated adenocarcinoma of unknown primary involves the cytokeratin status (CK7 and CK20). Further organ-specific markers can be tested after analysis of CK7 and CK20 expression.^[5]

In the index case, CK7 immunopositivity was found; however, the patient was lost to follow-up and further markers were not done.

Extensive radiological examination and accurate subtyping of the primary tumor enable the pathologist to choose the apt immunohistochemistry marker panel and document the origin of the tumor.

The awareness of metastatic carcinoma as a differential diagnosis on cytology and identification of cytomorphological features can guide the surgeon and management of the patient.

The correct cytological interpretation is d.

A diagnosis of the pleural effusion cell block is a “malignant tumor.” The pleural effusion smear cells block showed tumor cells epithelioid, with significant atypical, prominent nucleoli and giant tumor cells, and nuclear deviation. In this case, the touch prep shows variably sized loose clusters and single cells with acinar formation. The cells show abundant eosinophilic cytoplasm. The nuclei have moderate-to-severe heteroplasia with occasional prominent nucleoli. At the time, “malignant tumor” was the most appropriate diagnosis. The differential diagnosis would include suspicion for carcinoma and other sarcomas.

Q2. Hematoxylin-eosin(HE) stained sections are prepared from the tissue cores [Figure 2] and show a solid, cellular neoplasm. What is your interpretation?

Non-small cell lung cancer (NSCLC)

The correct cytological interpretation is d.

Microscopic appearance: Tumor cells in the biopsy tissue were arranged in two ways: Adenoid structural area and solid area. A small amount of red blood cells could be seen.

In the cavity of the adenoid area, epithelioid tumor cells, conspicuous small nucleoli could be seen, and tumor cells had significant atypia. Short spindle cells could be seen in the solid area, some nuclei were large and biased. Moreover, some cells had cytoplasmic vacuoles, and a single red blood cell could be seen in individual cytoplasmic vacuoles.

No clear myxochondroid or no clear myxochondroid or hyaline matrix was found. IHC staining was as follows: Tumor cells did not express CKpan, TTF1, P40, and so on; so, epithelial cancer was not considered. Tumor cells expressed vascular markers such as CD31, and ERG positive; so, EHE specific antibody CAMTA1 was added and positive. T (1p36) (CAMTA1) gene translocation (+) was detected by FISH (Note: Red and green separation signals can be seen in >50% of tumor cells). Hence, we considered it as EHE, angiosarcoma differentiated in some areas with blood lakes.

The final diagnosis was EHE of the lung with angiosarcoma-like components.

EHE is a rare low-grade malignant angiogenic tumor that is most common in the lung and liver, always with multiple nodules.

EHE was first proposed by Weiss and Enzinger^[1] in 1982 and was easily misdiagnosed morphologically as cancer. Its biological behavior was between epithelioid hemangioma and epithelioid angiosarcoma, which was defined as intermediate tumors. Along with the in-depth understanding of the disease, more studies^[2,3] found that the tumor had a relatively high local recurrence rate (10–15%), metastasis rate (20–30%), and mortality (10–20%), which far exceeded the definition of rare recurrence and rare metastasis of intermediate tumors. Therefore, EHE was classified as a low-grade malignant tumor.^[4] EHE often occurs in the lung and, or liver, typically as multiple nodules; however, it could occur in any body part, including bone, soft tissue, and heart.^[5]

Morphologically, mucinous cartilage-like matrix or hyaline degeneration, the tumor cells were arranged in a cord or nest shape. The tumor cells were relatively uniform in size, round, and oval. The nuclear chromatin was consistent, and the nucleolus was not prominent. The cytoplasm was light eosinophilic, or the nucleus was biased. Moreover, vacuoles could be seen in some cytoplasm containing single or multiple red blood cells, which are called vesicular cells. It suggested the formation of a vascular lumen. Nuclear mitosis and necrosis were rare in classic EHE tumors.

Many studies have reported the morphological characteristics and diagnostic criteria of atypical EHE. The morphological criteria of atypical EHE vary in different studies, including tumor size, necrosis, nuclear grade, and threshold of the mitotic count. Anderson et al. reported a clinicopathological study of 52 cases of thoracic epithelioid malignant vascular tumors.^[6] This showed epithelioid vascular tumors involving the chest divided into low-grade EHE, moderate EHE, and highly malignant epithelioid angiosarcoma with 4-year survival rates of 83%, 22%, and 9%, respectively. Studies have shown that the prognosis of moderate EHE was significantly worse than that of low-grade EHEs. In addition, survival analysis also showed that pleural involvement was a poor prognostic indicator. Similarly, the EHE of the pleura previously reported in our research group had a poor prognosis.^[7] This patient had pleural involvement and pleural effusion. The examination report showed that the prognosis was poor. Deyrup et al.^[2] performed a morphological risk assessment on the biological behavior of 49 cases of soft-tissue EHE. The risk model showed that a maximum tumor diameter >3 cm and mitosis >3/50 HPF were significantly correlated with poor patient prognosis. Therefore, the EHE could be divided into a high-risk group and a low-risk group. Shibayama et al.^[3] scored 61 patients with EHE based on tumor size (i30 vs. >30 mm) and histological characteristics (typical vs. atypical). Survival analysis showed that the 5-year overall survival rates of the low (24 cases), medium (28 cases), and high (nine cases) risk groups were 100%, 81.8%, and 16.9%, respectively. Gong et al.^[8] discussed the clinicopathological features of EHE, diagnosis, and differential diagnosis of eight cases of atypical EHE. They found that there were high-grade nuclei, active mitosis, solid flake growth mode, and tumor necrosis in the morphology of atypical EHE, and the biological behavior was more invasive. The follow-up results showed that there were six cases of metastasis, of which three cases died, and the prognosis was worse than that of classical EHE. Certain lineage changes in the morphology of EHE are significantly related to the prediction of patients. Therefore, how to accurately grade and guide the clinical treatment of EHEs will be the direction of future research.

EHE tumor cells express the vascular markers CD31, CD34, ERG, and FLI1. Cytokeratin can be expressed in 25% ~ 30% of cases, especially in biopsy specimens, which may be misdiagnosed as poorly differentiated carcinoma.^[5] In addition, EHE highly expresses CAMTA1. EHE with vascular lacuna generally does not express CAMTA1 but is TFE3 positive. However, it should be noted that TFE3 immunohistochemistry is not completely specific. Both CAMTA1 and TFE3 were nuclear positive in this case, but CAMTA1 gene translocation was detected.

Atypical EHE and epithelioid angiosarcoma can cross and migrate morphologically. The application of IHC markers and the detection of specific fusion genes are very essential for differential diagnosis. Approximately 90% of EHE can produce t (1; 3) (p36.3; q23-25) ectopically, resulting in the WWTR1-CAMTA1 fusion gene, while about 5% of EHE contains the YAP1-TFE3 gene fusion. Studies have shown that EHE of ectopic fusion of the WWTR1 gene is rarely reported and mainly occurs in the heart.^[3] The previous literature reported that epithelioid angiosarcoma could express the CAMTA1 marker, but the above fusion genes were not found.^[6,8] Yang et al. compared the detection of CAMTA1 expression in cases of EHE and other vascular tumors using FISH and IHC. The sensitivity and specificity of IHC were 85.7% and 100%, respectively, whereas the sensitivity and specificity of FISH were both 100%.^[9] Therefore, the detection of fusion genes is very important to distinguish EHE and epithelioid angiosarcoma.

Pulmonary EHE intersects with poorly differentiated adenocarcinoma, epithelioid angiosarcoma, and epithelioid hemangioma, which need to be differentiated according to microscopic morphology, IHC, and molecular detection.

EHE has limited experience in treatment, and more radical treatment may be needed. Therefore, surgical resection should ensure that the cutting edge is negative, supplemented by radiotherapy, chemotherapy, and targeted therapy if necessary.^[25] This patient is currently undergoing the third PC chemotherapy regimen. EHE in the lung will indicate a poor prognosis if accompanied by pleural effusion or spindle tumor cell components. In this case, pleural effusion was obvious, and an angiosarcoma area appeared, which may be related to the poor prognosis of the patient.

A rare case of epithelioid hemangioendothelioma transforming from some areas to epithelioid angiosarcoma was discussed. Under a microscope, except for the classic EHE area, vascular lacuna formation was seen in some areas. Tumor cell atypia, mitotic imaging, and proliferative activity were significantly higher than those in the EHE area. IHC techniques and FISH detection confirmed that CAMTA1 gene translocation occurred in this case. Vascular lacunae and tumor cell atypia were found in some areas, suggesting that they may be transformed into epithelioid angiosarcoma.

A case of EHE with epithelioid angiosarcoma of the spine is reported in the literature,^[26] but there was no genetic confirmation. From atypical morphology to final accurate diagnosis benefitting from immunohistochemistry and molecular diagnosis, we learned the development process of disease progression. We should not only recognize the classic morphology but also find clues regarding the classic morphology in atypical patients to provide a basis for accurate clinical diagnosis and treatment.

The patient received chemotherapy (albumin paclitaxel 420 mg/dL, carboplatin 680 mg/dL) combined with bevacizumab (400 mg/dL) injection intravenously on January 26, 2022. At present, the fourth course of treatment has been carried out. The current situation was stable.

From atypical morphology to final accurate diagnosis benefitting from immunohistochemistry and molecular diagnosis, we learned the development process of disease progression. We should not only recognize the classic morphology but also find clues regarding the classic morphology in atypical patients to provide a basis for accurate clinical diagnosis and treatment.

CT - Computed Tomography

EHE - Epithelioid Hemangioendothelioma

FISH - Fluorescence in situ Hybridization

HE - Hematoxylin-Eosin staining

IHC - Immunohistochemical

NSCLC - Non-small Cell Lung Cancer.

The manuscript was approved by all authors for publication. Substantial contributions to the conception, drafting the work and the acquisition, analysis of data for the work: S Z; Reviewing it critically for important intellectual content, and interpretation of data for the work: C W; Agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy, complete the Fish for the work, and interpretation of data for the work: W W;Design of the work, reviewing it critically for important intellectual content, and resolved any part of the work appropriately: L H. All authors contributed to editorial changes in the manuscript. All authors read and approved the final manuscript. All authors have participated sufficiently in the work and agreed to be accountable for all aspects of the work.

The Institutional Review Board of Shanghai Pulmonary Hospital approved this retrospective study (IRB NO. K22-081Y).

Written informed consent was obtained from all the participants prior to the publication of this study.

The findings in Pap smear [Figure 1] may represent all except

Low-grade squamous intraepithelial lesion (LGSIL)

a. Low-grade squamous intraepithelial lesion (LGSIL)

LGSIL (Option a) is characterized by distinct cytological features. The cells exhibit nuclear enlargement, typically 3 times the normal size without significantly high nuclear to cytoplasmic (N/C) ratio. Koilocytic changes include hyperchromasia along with coarse chromatin and nuclear membrane irregularities with diagnostic empty perinuclear cytoplasmic space sharply demarcated from peripheral cytoplasm. Binucleation and multinucleation are is frequent. Nucleoli are generally inconspicuous or absent. Low-grade squamous intraepithelial lesion may show increased keratinization seen as dense orangeophilic (atypical parakeratosis).^[1]

This is a case of recurrent uterine carcinosarcoma (UCS). The patient presented with chief complaints of abnormal vaginal bleeding for the past 1 month. Four years before this consultation, the patient underwent total abdominal hysterectomy, bilateral salpingo-oophorectomy (BSO), and pelvic lymph node sampling. Evaluation of the hysterectomy of the specimen revealed a stage IB UCS. She underwent chemotherapy; however, after 2 cycles, her thrombocytopenia got exacerbated, and chemotherapy was terminated.

During the present consultation, rectovaginal examination revealed a mass on the left vaginal apex. On CT scan, chest/ abdomen/pelvis revealed a 2.9 × 2.0 cm vaginal mass. There was no evidence of metastatic disease in the chest, abdomen, or pelvis. Pap smear and concurrent left vaginal biopsy were done. Pap smear revealed a biphasic neoplasm composed of atypical glandular cells with a spindle cell component. The malignant glandular component was comprised three-dimensional hyperchromatic crowded cell groups with high N/C ratio, coarse clumped chromatin, and occasional prominent nucleoli, whereas spindle cell components demonstrated high N/C ratio, hyperchromasia, irregular chromatin, and nuclear pleomorphism.

Histopathological examination (H&E) of the left vaginal biopsy [Figure 2a and 2b] revealed high-grade carcinoma with sarcomatoid features. Immunohistochemistry demonstrated [Figure 2c] focal immunoreactivity for cytokeratin CAM 5.2 [Figure 2d] with mutant p53 expression [Figure 2e] and nonimmunoreactivity for desmin [Figure 2f].

Based on cytology and vaginal biopsy findings, a diagnosis of vaginal cuff recurrence of carcinosarcoma was made, and the patient underwent external beam radiation therapy and vaginal brachytherapy.

Depending on multiple variables from cytomorphological features sampled in the Pap smear to the interpreter experience adenocarcinoma (Option c) and the carcinomatous component of UCS may have to be interpreted as atypical glandular cells of uncertain significance (AGUS) (Option b). However, the presence of spindle cells and the patient’s history of UCS would point to the definitive interpretation as carcinosarcoma (malignant mixed Mullerian tumor).

A biphasic neoplasm showing both a malignant epithelial component and a spindle cell/mesenchymal component on a Pap smear should raise the suspicion for the possibility of carcinosarcoma.^[2-5] It is reported that the detection rate of malignant cells in cervical samples of histologically proven UCS ranges from 56% to 70%;^[2-5] however, UCS usually lacks the sarcomatous component in Pap smears.

The carcinomatous component of UCS is more readily identifiable than the mesenchymal component [Table 1].^[2-8]

This is an important diagnostic pitfall in cytology as most cases of UCS may be reported as AGUS, squamous cell carcinoma, endometrial adenocarcinoma, poorly differentiated carcinoma, or adenocarcinoma not otherwise specified.^[5]

Detecting UCS through cytologic examination poses diagnostic challenges due to several factors. These challenges include sampling errors, random exfoliation of cells, cellular degeneration, and sporadic shedding of mesenchymal component.^[4] In addition, frequent association with atrophy can also make it difficult to detect UCS cells in the background of numerous HCGs of parabasal cells (PBC) in atrophic samples during cytologic examination of Pap smears.^[7]

In the current case, on initial review, the smear was interpreted as a hypercellular smear with an inflammatory background, cellular degeneration, and numerous malignant glandular cells in clusters and three-dimensional balls [Figure 1a and 1b], raising the possibility of AGUS favoring neoplasia, but HR-HPV testing was negative. After re-reviewing the smear, HCGs composed of a few cigar-shaped spindle cells [Figure 1c] suggestive of a mesenchymal component was identified. The final diagnosis of high-grade carcinoma with sarcomatous features were rendered. The cytologic findings were consistent with the vaginal biopsy results.

It is important to consider that, while HPV testing is a helpful tool in cervical cancer screening, a negative high-risk HPV test does not automatically exclude malignancy, because some malignancies arising in the uterine corpus or adnexa can be identified in cervical smears due to exfoliation, drop metastasis, and/or direct extension to cervix, such as UCS endometrial carcinomas, clear cell carcinoma, high-grade serous carcinoma, and mesonephric adenocarcinoma are not HPV related.

Furthermore, there are other aggressive cancers such as endometrial carcinomas, clear cell carcinoma, high-grade serous carcinoma, mesonephric adenocarcinoma, and adenocarcinomas arising from other sites that show high-grade morphology in Pap smears despite testing negative for HPV.^[9,10]

One of the potential reasons for the initial omission of the mesenchymal elements is the frequent association of atrophic changes in the elderly patients with abundant inflammatory cells and cellular degeneration with many HCGs of PBCs in Pap smears. Another possibility could be the inability to detect spindle cells/mesenchymal elements in Pap smear on the first look as the mesenchymal element with atypical spindle cells [as in the current case, Figure 1c, and arrows in Figure 1d] is rarely present due to infrequent shedding and sampling artifacts.

It is crucial to understand that a significant percentage of women with AGUS may turn out to be high-grade pre-invasive squamous disease, adenocarcinoma in situ, adenocarcinoma, or invasive cancers from sites other than the cervix. Owing to the aggressive nature of UCS, an accurate and timely diagnosis is indispensable. An algorithmic approach is suggested for interpreting AGUS cells in relation to UCS Pap smear [Figure 3].

UCS, previously known as malignant mixed Müllerian tumor, is a rare and aggressive biphasic tumor in the female reproductive system, accounting for <5% of uterine tumors. It is characterized by the presence of high-grade epithelial and mesenchymal components. UCS is commonly diagnosed in postmenopausal women with a history of bleeding with a median age of presentation of 62 years.^[11] The most common locations within the female genital tract include the uterus and ovaries. Cases of UCS originating from the cervix, vagina, ovary, fallopian tube, and peritoneum are also reported.^[11]

It is biologically a de-differentiated endometrial carcinoma with its own pathogenesis and molecular profile.^[12] Several hypotheses to explain the origination of UCS have been proposed. The collision hypothesis suggested that UCS forms when separate epithelial and mesenchymal tumors collide and merge within the uterus. On the other hand, the combination hypothesis posits that UCS arises from a single stem cell capable of divergent differentiation, giving rise to both epithelial and mesenchymal components within the tumor. Finally, the conversion hypothesis, which is the most widely accepted theory proposed that UCS is a metaplastic carcinoma that carcinomatous cells can undergo a conversion process where they transform into sarcomatous cells through epithelial to mesenchymal transition (EMT).^[13,14] This conversion is associated with high scores of EMT gene signatures and is likely influenced by epigenetic alterations at microRNA promoters, histone gene mutations, and gene amplifications.^[14]

TP53/p53 abnormalities are present in a majority of the UCS. The proportion of replicative DNA polymerase epsilon (POLE) and hypermutated microsatellite instability-high is related to the epithelial component, being approximately 25% and 3% in endometrioid and non-endometrioid components.^[15] The stage at diagnosis follows a bimodal distribution, approximately 40–50% of cases are detected at an early stage (International Federation of Gynecology and Obstetrics [FIGO] Stages I and II), while about 50–60% are detected at an advanced stage (FIGO stages III and IV). At the time of diagnosis, up to 30–40% of patients display lymph node metastases. In addition, about 10% of patients present with distant metastatic spread, with lung as the commonly affected site. These findings highlight the aggressive nature of UCS and the importance of early detection and intervention. The 5-year survival rate of UCS is approximately 30% (Stage I and II: 59%; Stage III: 25%; Stage IV: 9%).^[16]

Histologically, the malignant cell in UCS exhibits a biphasic nature; the carcinomatous component is usually endometrioid or serous, but clear and undifferentiated may be seen. The sarcomatous component is usually high-grade sarcoma NOS, but heterologous elements (rhabdo, chondro, osteo, and lipo) might be encountered.^[17,18]

Recommended treatment for UCS involves surgical staging with total hysterectomy with BSO, pelvic lymphadenectomy, para-aortic lymph node sampling, and peritoneal washings.^[19]

The Pap smear can serve as both a screening and diagnostic tool.

Answers for Question 2 through 3:

2. a

PEH is an exuberant intravascular, endothelial cell proliferation mimicking a neoplastic tumor of vascular origin with papillary tufting and “hobnail” morphology.^[1] Although initially described as a neoplastic lesion by Masson,^[7] it is now considered as reactive vascular proliferation with an organized thrombus.^[8] In its pure form, as in our case, it occurs in dilated veins of the head, neck, limbs, and trunk. It can also engraft in pre-existing vasoformative lesions. In the early lesions, numerous small, delicate papillae with a hyalinized core lined by plump endothelial cells invaginate into the lumen with tufting growth and “hobnail” morphology as in our case.^[2-5] During the late stage, the fusion of the papillae results in an anastomosing network of vessels embedded in a loose, meshlike stroma of connective tissue.^[1] Rupture of the vein can result in the passive extension of the lesion into the surrounding soft tissue.^[1] The prognosis is generally excellent. Essentially, all cases are treated and cured by simple excision.^[1] Recurrent lesions are generally secondarily superimposed on preexisting vasoformative lesions.^[1]

Papillary endothelial hyperplasia carries a significant potential for misdiagnosis as angiosarcoma. Cytopathological diagnosis of this uncommon reactive vascular lesion is difficult only on FNA findings. A vascular lesion may be considered, especially when polygonal cells with plump nuclei and “hobnail” morphology are seen in a hemorrhagic background. The cytological differential diagnoses to be considered include the common neoplastic vascular lesions. Histomorphology of the resected specimen helps provide conclusive evidence in excluding the neoplastic nature of the vascular lesion.

What are the symptoms of AL amyloidosis?

Shortness of breath

Answer(s):

d. All of the above

AL amyloidosis is generally found in older men. General symptoms of AL amyloidosis include abnormal bleeding, dizziness, fatigue, shortness of breath, and muscle weakness.^[5] AL amyloidosis also hinders the function of specific organs. A build-up of amyloid proteins in the kidneys can cause chronic kidney disease (renal AL amyloidosis).^[5] Accumulation of amyloid proteins in the heart (AL cardiac amyloidosis) can cause heart palpitations, arrhythmia, shortness of breath, fatigue, as well as thickening of heart tissues increasing the chance of heart failure.^[5] In the gastrointestinal tract, escalation in amyloid proteins can cause weight loss, abdominal pain, constipation, diarrhea, gastric reflux, and vomiting.^[5] Amyloid proteins can also develop in the central nervous system causing changes in blood pressure, erectile dysfunction, pain in the hands, feet, and lower legs, as well as confusion.^[5] Unlike some forms of amyloidosis, AL amyloidosis cannot be transmitted genetically.^[3]

What treatments are implicated on a patient with AL amyloidosis?

Chemotherapy

Answer(s):

e). All of the above

There is no known cure for systemic AL amyloidosis. Chemotherapy, like that used in cancer patients, is typically prescribed to slow down the build-up of amyloid proteins by killing cells that produce them.^[6] Another method is bone marrow transplant, also known as a stem cell transplant. Patients with localized amyloidosis do not receive treatment, instead, the mass is removed if it affects organ function; otherwise, the mass can be left in the body.

What is the latest method of confirming a clinical diagnosis of amyloidosis?

Blood test

Answer:

c). Anterior fat pad FNA biopsies with mass spectrometry/ proteomics

Earlier, abdominal fat biopsies for confirming amyloidosis relied on electron microscopy and Congo red staining.^[7] Now, better tests for diagnosis are available, and FNA samples can be aspirated successfully^[8,9] and processed using laser dissection, mass spectrometry, and proteomics.^[10] Rectal mucosal biopsies have been replaced by anterior abdominal wall fat pad FNA technique as shown in videos.^[8,9]

AL amyloidosis is a rare condition typically found in older male patients. Initial diagnosis of AL amyloidosis usually involves Congo red staining, looking for apple-green birefringence. Mass spectrometry recognizes all amyloid types (AL vs. AA vs. transthyretin/hereditary) and can easily be performed on formalin fixed, paraffin embedded tissue from core biopsies, and cell blocks. It confirms the diagnosis, identifies specific mutations, and helps guide appropriate treatment.

Degenerated cells

The correct cytopathological interpretation is d. Small blue round cell tumor.

Cytocentrifuge smears prepared were cellular comprising of monomorphic tumor cells arranged in clusters and nests. Individual tumor cells are round to ovoid having scant to moderate amount of delicate cytoplasm. Nuclei were regular, smooth with opened up chromatin, showing mild-to-moderate degree of pleomorphism [Figure 1a-c]. Atypical mitosis was noted. However, rosette or acini formation or necrosis or moulding was not seen.

The cells were cohesive with no acini formation, delicate chromatin and no nucleoli thereby ruling out adenocarcinoma (Option b).

No glial matrix or fibrillary processes or rosenthal fibres or vessels or calcification or cellular pleomorphism or endothelial cell proliferation were displayed hence possibility of glioma was also excluded from the study (Option c).

Degenerated cells (Option a) were seen but most of the cells were preserved and had distinct cell boundary with nuclear margins and cellular details as discussed briefly above. Based on findings described above, a provisional diagnosis of small blue round blue cell tumor was considered. Cell block and immunocytochemistry could not be performed due to exhaustion of fluid while making smears for routine examination.

Excision surgery was performed and histopathological examination revealed a tumor [Figure 2a and b].

All of the following are among the differentials except

Germ cell tumor

Histopathological examination revealed tumor cells arranged in nests, chords and trabeculae showing moderate degree of pleomorphism. Cells were round to oval with stippled nuclear chromatin [Figure 2a and b]. Areas of hemorrhage and focal areas of necrosis were also seen. Mitotic figures of 2–3/10 high power field noted. The various differential included are neuroendocrine neoplasm (NEN), germ cell tumor, melanoma, and lymphoma.

Astrocytoma (option b) will show tumor cells having irregular nuclei with variable degree of atypia along with presence of glial processes. Cells can have variable cellular morphology in a fibrillary background which is not seen in this case.

Initial panel of immunohistochemistry (IHC) was applied which included Glial fibrillary acidic protein (GFAP), LCA, SALL4, CK7, CK20, CD117, desmin, myogenin, CD99, HMB 45, and S-100. All above markers came out to be negative except focal pan-cytokeratin positivity [Figures 3a-e]. A secondary panel of synaptophysin and chromogranin applied was positive. KI67 proliferation index was >20%.

Which marker helped in excluding the primary nature of the lesion?

Synaptophysin

GFAP is positive in intermediate filament of astrocytes. In the present case, it was negative in the tumor cells.

Synaptophysin and chromogranin are markers for neuroendocrine cells whereas pancytokeratin indicates the epithelial nature of the lesion.

All further IHCs can be put to check for the metastatic site of NEN except

Insulinoma associated protein 1 (INSM-1)

Insulinoma associated protein 1 (INSM-1) is a nuclear marker of neuroendocrine differentiation with better sensitivity and specificity as compared to synaptophysin, chromogranin, and CD56.

CDX2 helps in location metastasis from colon whereas TTF-1 from lung.

On extended IHC, the cells were focally positive for TTF-1 [Figure 4] while negative for Napsin-A and CDX2.

A Positron emission tomography/Computed tomography (PET/CT) was performed which showed metabolically active soft tissue density lesion measuring 2.5 × 1.7 × 2.5 cm in the upper lobe of left lung in the para mediastinal aspect with metabolic activity in the mediastinal lymph nodes. The above PET/CT findings further confirmed the histopathological diagnosis of tumor arising in lung.

NEN can develop at any of the initial mentioned systems where the neuroendocrine cells are present.^[1] Incidence of central nervous system (CNS) metastasis is very rare and accounts 1.5–5% of all patients^[2] where NEN source found to be in 1.3–1.4% in all cases of CNS metastasis.^[3] It is always a challenging task to detect primary focus, because patients have specific symptoms when the tumor size is small. Radiological investigations including somatostatin scintigraphy and PET/CT proved to be very useful. Metastatic disease in addition to differentiation and proliferation rates is an important prognostic factor in NEN. Presence of brain metastasis is usually found to be characteristic of a systemic dissemination and disease progression.

Cytological features of neuroendocrine tumors are described in literature that includes monomorphic population of cells, loosely cohesive fragments, medium in size having abundant cytoplasm, and very few mitotic figures. Occasional rosette formation can be seen. Nuclei were regular, smooth with opened up chromatin, showing mild-to-moderate degree of pleomorphism [Figure 1]. Occasional cells showed prominent nucleolus. Atypical mitosis was seen. Due to variation in the cytomorphological features of neuroendocrine tumor, they mimic a variety of tumors. The features range from discrete cells to tight cohesive clusters, hyperchromatic nuclei with basophilic to granular to scant cytoplasm. Nuclear moulding may or may not be seen. Pleomorphism can be seen.^[4]

In the present case, diagnosis of metastatic neuroendocrine tumor Grade 3 was made. TTF-1 positivity pointed out the brain tumor was metastatic, which was later confirmed by PETCT that exhibited a primary lesion in the lung. The grading of neuroendocrine tumors (NET) is based on Ki67 proliferation index. However, in neuroendocrine carcinomas, also it is advised for distinguishing it from Grade 3 NETs.^[5] Features favoring neuroendocrine carcinoma are dirty smear with areas of necrotic debris and very scant cytoplasm in small cell type whereas abundant in large cell type. The population of cells having salt and paper chromatin, severe nuclear fragility, and many atypical mitoses.^[2,6] Only limited previous case reports are available discussing NEN initial presentation as brain metastasis,^[7-11] one of which was reported as a primary brain NEN of third ventricle adjacent to which in the paraventricular nucleus resides group of neuroendocrine cells.^[12] Mostly by the time patient presents with brain metastasis either metastasis to lung happens or develop primary lung tumor. The metastasis to brain occurs due to hematogenous spread of the tumor. Leading cause of death in patients with CNS NENs is secondary to systemic disease progression and a better 10-year overall survival rate is seen in primary brain NENs.^[13] Imaging workup holds importance where CT imaging has sensitivity of 95% in identification of primary tumor.^[14] Etoposide -platinum chemotherapy is the treatment of choice in grade 3 NEN.^[15] In metastatic brain NENs, radiation therapy and surgery are found to be beneficial but more research is required for proper management of primary brain NENs.^[16]

Metastatic disease is a major prognostic factor in NEN s in addition to differentiation and proliferation rate. Brain metastasis of neuroendocrine carcinoma is a rare entity but the possibility of it should be borne in mind for accurate diagnosis. In the present study, patient has been on regular follow-up for 9 months and is living disease free while continuing on etoposide chemotherapy.

Q1. What is your diagnosis for the above findings?

Squamous cell carcinoma.

The answer is (c).

Uterine carcinosarcoma, also known as malignant mixed Mullerian tumor (MMMT), is a rare and aggressive form of corpus uteri tumor. The tumor is composed of two cellular components: Epithelial and mesenchymal. The cervical smear findings showed both cellular components which raised the suspicion of carcinosarcoma. Endocervical adenocarcinoma can be a differential; however, the presence of large rhabdoid cells and tissue fragments of round to oval hyperchromatic nuclei with scant cytoplasm cells excluded adenocarcinoma. Squamous cell carcinoma (SCC) was excluded since the spindle cells that are present in this case look different from pleomorphic cells such as “tadpole” and “fiber” cells that are seen particularly in keratinizing type of SCC. Also, the lack of high-grade squamous intraepithelial lesion which did not favor the diagnosis of SCC. Hence altogether, the final report concluded that carcinosarcoma is the most likely correct diagnosis.

Q2. What are the following immunohistochemistry markers will be positive to confirm the diagnosis of carcinosarcoma?

CD56, desmin, α-smooth muscle actin (SMA), MyoD-1, AE1/AE3, and tumor protein 53 (P53)

The answer is (a).

Immunohistochemical markers on sarcomatous components were positive for cluster of differentiation 56, and desmin and focal positivity for α-SMA and MyoD-1 [Figure 3a-d]. In the malignant epithelial components, AE1/AE3 and P53 showed positivity in more than 80% of the cells in keeping with serous carcinoma [Figure 3e].

Q3. All of following are heterologous component of carcinosarcoma, except for?

Osteosarcomatous

The answer is (d).

MMMT, also known as carcinosarcoma, is a rare and aggressive form of corpus uteri tumor. The tumor is composed of two cellular components: Epithelial and mesenchymal which commonly arise from the endometrial cavity.^[1] Despite carcinosarcoma cases currently comprising <5% of all uterine tumors,^[2] there is an evidence to suggest that there is an increase in the incidence of carcinosarcomas.^[3] Hence, it becomes increasingly important for cytologists to be aware of the cytological features for diagnosing this form of tumor. Our cytological findings showed highly atypical epithelial and spindle cells, suggestive of a biphasic tumor type. In addition, a tumor diathesis is reported to be characteristic features of carcinosarcoma in cytological cervical smears.^[4,5]

Our cytological features overlapped with previously described reports,^[4-6] indicating that carcinosarcoma should always be considered in cases where malignant epithelial and spindly cells are found on a dirty background, especially in women presenting with postmenopausal bleeding.^[7] In contrary, other studies have indicated that sarcomatous components are rare findings in cytological smears which make diagnosis of carcinosarcoma difficult.^[6,8] A study by Hanley et al. showed that around 72.5% of carcinosarcoma patients had an abnormal Pap smear; however, the majority lacked cytological features consistent with a sarcomatous component.^[9] In addition, a study showed that Pap smear test has low overall sensitivity (41.8%), but higher specificity (60.8%) for detecting uterine glandular lesions, which suggest that cytological findings should be confirmed by histological and immunochemical markers.^[10]

Uterine carcinosarcoma is a malignancy of two components; epithelial (carcino-) and mesenchymal (-sarcoma), and it can be classified as homologous or heterologous types. The homologous type involves a sarcomatous component of intrauterus such as fibrosarcoma, endometrial stromal sarcoma, and leiomyosarcoma, whereas heterologous component involves cells of extrauterine connective tissues such as rhabdomyosarcoma and chondrosarcoma.^[11] In the present case, the malignant epithelial components are positive for P53 and p16 in keeping with serous carcinoma. While the sarcomatous component with rhabdoid differentiation was positive for MyoD-1 and desmin and negative for h-caldesmon, demonstrating a heterologous uterine carcinosarcoma, consistent with previously reported case.^[12]

This case was challenging since the Pap smear request was received from a peripheral hospital with limited clinical and radiological details. Furthermore, this tumor commonly occurs in postmenopausal women, with one of the most frequent clinical manifestations being postmenopausal bleeding. However, in this case, the patient presented with the lower abdominal pain and dysuria. Nevertheless, the presence of all the classic cytological features of carcinosarcoma enabled a successful diagnosis of this rare tumor in a Pap smear.

Carcinosarcoma of the uterine wall may extend to cervix and present in cytological cervical (Pap) smears. Awareness of the possibility facilitates an optimal diagnosis and appropriate management.

What is your most probable diagnosis?

Metastatic renal cell carcinoma

d. Metastatic Hurthle cell carcinoma.

The scalp swelling was [Figure 1a] on CECT brain revealed a destructive, mildly enhancing bony mass lesion with intra- and extra-cranial extension in the left parietal bone [Figure 1b]. The aspirate from scalp swelling of moderate cellularity showing round cells with central nucleus with nuclear dysplasia in the form of high nucleocytoplasmic ratio, nuclear enlargement, mild-to-moderate pleomorphism, and binucleation [Figures 1c, d and 2a, b]. In addition, some of the groups of cells also had presence of fire flares. The thyroid function test was within normal limits. No mass lesion was seen in kidneys on ultrasound. CECT neck showed few hypodense and calcified nodules in bilateral thyroid lobes. Ultrasound-guided aspirate from thyroid showed similar morphology as seen in scalp swelling [Figure 3a and b]. Final diagnosis was metastatic Hurthle cell carcinoma (HCC) of thyroid.

Who gave the description of Hurthle cells?

Max Askanazy

a. Max Askanazy.

HCC is a rare differentiated thyroid carcinoma of follicular origin, and it accounts for approximately 3–7% of all thyroid carcinomas.^[1] Max Askanazy, in 1898, described the Hurthle cells/Oncocytic cells in Graves’ disease and Karl Hurthle described the C cells. James Ewing, in 1919, wrote the textbook “Neoplastic Diseases,” described large, granular eosinophilic cells in thyroid carcinoma, and named them Hurthle cells of the thyroid alveoli. Since then, the “Hurthle cell” term has been used in the literature for the cells that were originally described by Max Askanazy, and it is a misnomer.^[2]

In the recent, the World Health Organization (WHO) classification of Tumors of Endocrine Organs published in 2017, how the HCC is classified?

Variant of follicular carcinoma

HCC has traditionally been classified as a variant of follicular carcinoma of the thyroid, but it was reclassified as a separate entity under the differentiated thyroid carcinomas in the 4^th WHO classification of Tumors of Endocrine Organs in 2017, because it has a distinct clinical presentation, pathological features, and genetic profile.^[3] The present case is being reported due to the rarity of HCC in the thyroid and even rarer is its primary presentation as scalp swelling without any palpable mass in the thyroid.

Hurthle cells are also known as oncocytic/oxyphilic/ eosinophilic cells. Hurthle cell change is observed in a variety of thyroid entities ranging from benign to malignant (including lymphocytic/Hashimoto thyroiditis, nodular goiter, long-standing chronic hyperthyroidism, Hurthle cell adenoma, and HCC), and it is not specific to any single entity.^[4] Hurthle cell tumors with malignant behavior show metastasis to the lungs, bones, lymph nodes, and brain.^[5] Bone metastasis has been reported in 10–40% of cases, with skull bone metastases only in 2.5–5.8% of cases.^[6] Lymph node metastasis is also observed in various studies, ranging from 9% to 20%.^[7] Sometimes, the primary presentation of thyroid carcinoma is a metastatic lesion, and the present case is one such rare example. If the cytomorphology shows a follicular pattern along with the classic malignant nuclear features in fine-needle aspiration (FNA) of metastatic sites, diagnosis of HCC on FNA is also possible. HCC can be misdiagnosed as some oncocytic neoplasms from other organs are also present with Hurthle/oncocytic cells with granular cytoplasm, central nucleus, and bland chromatin. In such cases, it is imperative to take into consideration the other clinical and radiological features before making a definitive diagnosis. In cutaneous metastatic lesions, apocrine cells of sweat glands, granular cell tumors, and adnexal tumors of skin with apocrine differentiation may create confusion with Hurthle cells.^[8] Granular cell tumor, on cytology, shows tumor cells predominantly in cohesive/syncytial pattern, as well as scattered singly with ill-defined abundant granular cell borders. Tumor cell nuclei show pleomorphism ranging from round/oval to spindle cells. These cells are slightly smaller in size compared to cells of HCC and tumor cells of HCC have well-defined cytoplasm.^[9] Cytomorphology of metastatic renal cell carcinoma may show round to oval tumor cells in clusters, sheets, acini, and papillaroid fragments with pale to clear foamy and vacuolated cytoplasm. Some of the cells may show adherence to endothelial cells. There can be mild-to-moderate cellular and nuclear pleomorphism. Foamy cytoplasm on cytology in some cases can help it to differentiate from HCC. However, ancillary studies and radiology are required for making a definite diagnosis.^[10] Primary adnexal tumor of skin includes clear cell hidradenoma which shows biphasic cell population comprising of round to polygonal cells with eosinophilic cytoplasm and vesicular nuclei; other population of cells include clear cells containing glycogen with eccentric nuclei.^[10] HCC is usually treated with total thyroidectomy and skull metastasis by excision of the lesion.^[6] However, there are no consistent guidelines or recommendations for the treatment of skull metastasis.^[6] Total surgical clearance of foci of tumor can be achieved with total thyroidectomy and follow-up of the patient for recurrence or metastasis can be done using thyroglobulin marker.^[6]

As discussed in the present case, HCC can present as an isolated metastatic disease without palpable thyroid swelling. In such cases, cytomorphological features can point toward a possible primary in the thyroid and lead to an accurate and timely diagnosis. The case also highlights the importance of cytology, radiology, as well as clinical features to arrive at a definitive diagnosis and appropriate treatment in such rare cases.

Q1. What is the probable diagnosis?

Tuberculosis

Answer: C.

Idiopathic granulomatous mastitis (IGM)

Cytological diagnosis of granulomatous mastitis is challenging. Differential diagnoses include tuberculosis, fungal infections, sarcoidosis, and histiocytic disorders including Rosai-Dorfman disease. Cytological features of granulomatous mastitis include the presence of epithelioid cell granulomas, multinucleated giant cells, histiocytes with phagocytosed neutrophils, and numerous neutrophils.

Q2. Which type of cell is phagocytosed by histiocytes in IGM?

Lymphocytes

Answer: D. Studies have shown that the presence of neutrophils is an important diagnostic clue in diagnosing granulomatous mastitis, as in the present case, where histocytes showing emperipolesis of neutrophils along with the presence of numerous neutrophils in the background led to the diagnosis in this case. In contrast, Rosai-Dorfman disease shows emperipolesis of lymphocytes. However, in some cases of IGM, lymphocytes and eosinophils have also been seen in the smear or biopsy.

Q3. Based on various studies, which bacteria is associated with IGM?

Corynebacterium

Answer: D. There are many studies which have identified Corynebacterium as the dominant bacteria associated with IGM. But Streptococcus, Pseudomonas, Atypical Mycobacteria, and Actinomyces have also been identified. Various other etiology of IGM include autoimmunity and abnormal hormonal levels.

Q4. What is the treatment modality for IGM?

Steroid

Answer: D. Patients of IGM have good prognosis with steroids, antibiotics, and immunosuppressive therapy. In some refractory cases, where medical management failed, surgical excision is offered.

Granulomatous mastitis is a rare benign inflammatory entity described by Kessler and Wolloch in 1972.^[1] It commonly affects young women of childbearing age usually within a few years of lactation.^[2,3] The most common presentation includes a painful nodular lump along with induration and redness.^[4] The clinical presentation may mimic malignancy. Cytological diagnosis of the entity remains challenging due to overlapping features with many other conditions including tuberculosis, Rosai-Dorfman disease, and even malignancy.^[1,5]

Various risk factors were studied, but none were specifically related to granulomatous mastitis. Possible etiological factors include an inflammatory response to epithelial damage, Corynebacterium kroppenstedtii infection, autoimmune disease, foreign body reaction, and a previous history of antipsychotic medications. In addition, the correlation between granulomatous mastitis and breastfeeding and childbirth was also studied.^[3,4] The radiological features of the entity are non-specific.^[6] The present case did not have a history of medications. She had a history of breastfeeding 8 years ago. Cytological diagnosis of granulomatous mastitis is challenging. Differential diagnoses include tuberculosis, fungal infections, sarcoidosis, and histiocytic disorders including Rosai-Dorfman disease. Cytological features of granulomatous mastitis include the presence of epithelioid cell granulomas, multinucleated giant cells, and numerous neutrophils. The presence or absence of necrosis is not very specific as few studies demonstrated necrosis in all the cases while few studies report necrosis in only a few cases.^[2-5,7] Studies have shown that the presence of neutrophils is an important diagnostic clue in diagnosing granulomatous mastitis, as in the present case where histiocytes showing phagocytosed neutrophils along with the presence of numerous neutrophils in the background led to the diagnosis.^[2,7,8] The prominence of emperipolesis is not a common feature. Apart from infectious causes, the major differential diagnosis considered was Rosai-Dorfman disease of the breast, which also shows an abundance of histiocytes showing emperipolesis. However, the literature search revealed that the type of cells ingested by histiocytes differs in both cases. In the case of Rosai-Dorfman disease, it is the lymphocytes that are being found in the cytoplasm of histiocytes in contrast to neutrophils which are found in granulomatous mastitis.^[8] Other differential diagnoses include sarcoidosis, which shows naked granulomas in the absence of necrosis, which was not the case here. ZiehlNeelsen stain was performed to rule out tuberculosis, which did not reveal any acid-fast bacilli. Management of granulomatous mastitis includes antibiotics such as doxycycline, corticosteroids with or without surgery, or simple follow-up. Few refractory cases have shown improvement with methotrexate, although consensus on the optimal treatment method is lacking.^[9]

We discussed a case of granulomatous mastitis presenting in a middle-aged non-lactating woman with no previous history of psychiatric medications, contraceptive pills, or trauma who presented with a nodular lesion. The cytologic diagnosis is based on finding histiocytes with neutrophils, giant cells, and epithelioid cell granulomas with or without necrosis and excluding other common differential diagnoses such as tuberculosis and fungal infections. As far as IGM is concerned, there is no standard management approach. Therefore, treatment strategies should be tailored to the needs of each patient based on the culture report and response to initial medical management which avoids aggressive management.

What is your interpretation?

Negative for malignancy; mucinous cyst debris of uncertain etiology

The correct cytologic interpretation is: D. Atypical; cellular stromal elements with mononuclear cells and mild ductal epithelial atypia.

The FNA showed numerous fragments of fibrous tissue with a dense lymphomononuclear cell infiltrate present both within the stromal fragments and in the background. Lymphocytic counts of 27/60X field were identified. Plasma cells were less numerous (8/60X field). Immunocytochemical staining for immunoglobulin G4 (IgG4) performed on air-dried smears was non-contributory. Groups of ductal epithelium with mild nuclear atypia were noted. Material was not available for cell block. The case was signed out as, “Atypical; mild ductal epithelial atypia and chronic fibroinflammatory changes.”

The patient denied alcohol consumption but had a remote history of tobacco use. Prior to detection of the lesion, she had visited the emergency room on two occasions over a 3-month period due to epigastric pain accompanied by weight loss and anorexia. She eventually underwent cephalic duodenopancreatectomy. Macroscopic examination of the specimen revealed an ill-defined, tan, 4 cm lesion within the pancreatic head. Histologic sections of the lesion [Figure 2] showed dense lymphoplasmacytic infiltrates with perineural accentuation, storiform fibrosis, and acinar atrophy. Nonobliterative lymphoplasmacytic phlebitis and non-necrotizing obliterative arteritis were observed. Immunohistochemistry revealed over 50 IgG4-positive plasma cells per high power field and an IgG4 to IgG ratio of over 50%. These findings proved histologically highly suggestive of IgG4-related autoimmune pancreatitis (AIP).

The patient’s serum IgG4 level preoperatively was 85 mg/dL and postoperatively rose to 122 mg/dL. Both values were insufficient to meet the serological diagnostic criterion of 136 mg/dL for IgG4-related disease.^[1] However, clinical follow-up was significant for persistent enlargement of abdominal lymph nodes as well as elevated alkaline phosphatase and gamma-glutamyl transferase, presumed to represent IgG4-related lymphadenopathy and cholangiopathy. Prednisone and methotrexate therapy were initiated with subsequent resolution of lymphadenopathy and normalization of liver enzymes. The patient is asymptomatic 2 years after surgery.

It is important to be aware of mass-forming inflammatory lesions of the pancreas such as AIP which may clinically and radiologically simulate pancreatic malignancy sometimes leading to unnecessary surgical resection. Although EUS guided FNA (EUS-FNA) is often a useful adjunct in the diagnosis of pancreatic lesions, allowing for correct classification of many cases, the preoperative diagnosis of AIP based on EUS-FNA is challenging, and no widely accepted cytologic criteria have been reported.^[2,3]

Furthermore, benign features suggestive of AIP do not rule out false negative results induced by sampling error.^[4]

Q2. All of the following are suggestive of Type 1 AIP over Type 2 AIP, EXCEPT:

Systemic disease

Q3. All are pathological characteristics of Type 1 AIP, EXCEPT:

Lymphoplasmacytic inflammation with storiform fibrosis

Q4. Which of the following is true regarding the cytomorphologic findings of Type 1 AIP:

Fragments of cellular fibrous stroma are common

Q2. (d); Q3. (b); Q4. (a).

Q2. (d) AIP is a pancreatobiliary-centric inflammatory disease, typically marked by corticosteroid responsiveness and classified in two groups. Type 1 AIP often affects elderly males, associates extrapancreatic manifestations of systemic IgG4-related disease (including cholangitis, sialadenitis, retroperitoneal fibrosis, or lymphadenopathy), shows frequent relapses and elevation of serum IgG4 in approximately 80% of cases.^[5] In contrast, Type 2 AIP is considered to be an isolated pancreatic disorder and does not show elevation of serum IgG4. Recurrence is rare. Interestingly, Type 2 AIP is linked to inflammatory bowel disease (ulcerative colitis or Crohn’s disease), seen in up to 16–30% of Type 2 AIP cases.^[5,6]

Q3. (b) AIP most often involves the head of the pancreas.^[7] Type 1 AIP is histologically characterized by a dense lymphoplasmocytic infiltrate, storiform fibrosis, obliterative phlebitis, and increased numbers of IgG4 positive plasma cells, typically >50/high-power field, and IgG4+/IgG+ ratio of >40%.^[8] Lymphoplasmacytic arteritis and a preferentially perineural distribution of inflammation have also been described.^[8,9] Type 2 AIP is histologically characterized by periductal inflammation with granulocytic epithelial lesions and relative paucity of IgG4-positive plasma cells.^[10]

Q4. (a) EUS-FNA alone is widely considered to be insufficient to make a definitive diagnosis of AIP, probably at least partially due to a lack of architectural integrity.^[11] In fact, International Consensus Diagnostic Criteria for AIP (2011) list core/surgical biopsy specimens as preferable for diagnosis of AIP.^[12] Despite this, certain cytological findings in conjunction with clinicoradiological clues can aid in establishing a diagnosis AIP in certain cases. A recent retrospective review of AIP FNA results found that cellularity of stromal fragments was significantly higher in AIP than in the control group.^[2] Furthermore, stromal fragments with embedded lymphocytes (>30/60x) were seen in almost 40% of AIP cases versus 0% in chronic pancreatitis, NOS.^[2] Other authors have found that AIP is often reported as “atypical” on FNA, probably due to ductal epithelial atypia secondary to surrounding inflammatory and fibrotic changes.^[4] Performance of IgG4 immunolabeling on the cell block material and/or pre-operative identification of elevated serum IgG4 levels may provide valuable information. Unfortunately, as occurred in the present case, not all cases of Type 1 AIP demonstrate elevated serum IgG4 and cell block material was not available for evaluation.

Awareness of AIP’s potential to clinically and radiologically simulate pancreatic malignancy is important to avoid unnecessary surgery.

Although AIP on FNA lacks specific cytomorphologic features, cellular stromal fragments, mild ductal epithelial atypia and prominent lymphocytic infiltrate are common findings and may support the diagnosis in the proper context.

Corticosteroid responsiveness and elevated serum IgG4 are useful clues which, in conjunction with suggestive cytomorphology, may reduce gratuitous duodenopancreatectomy.

The correct cytological interpretation is b. Cysticercosis.

Aspirate was fluidy in this case and the smears showed large fragments of bladder wall identified as fibrillary bluish material woven into rounded multiple subcuticular cells with interspersed tiny blue pyknotic nuclei surrounded by dense inflammatory infiltrate. The background showed sheets of histiocytes, scattered eosinophils, neutrophils, and few multinucleated giant cells [Figures 1 and 2]. These features are characteristic of Cysticercosis. Cysticercosis is caused by larval stage of Taenia solium, while adult form causes Taeniasis.

The most common cytologic mimic of cysticercosis is other cestodes including hydatid cyst (Echinococcus granulosus), Coenuri and Spargana. The differentiation between these requires careful examination of the bladder wall and hooklets. The bladder wall is thin and membranous in cysticercosis while thick and lamellated in a hydatid cyst. The hooklets of cysticercosis are sized 130–170 m while hydatid hooklets range between 22 m and 44 m.^[1]

Filariasis (Option D) is another vector borne disease and shows microfilariae. Most common causative agents of human filariasis include Wuchereria bancrofti, Brugia malayi, Brugia timori, and Loa loa.

Q2. What is the mode of transmission of the disease?

Feco-oral contamination

Q3. All of the following statement are true for cysticercosis, except?

Cysticercosis is caused by larval stage of T. solium

Answers: Q2-a, Q3-b.

The life-cycle of T. solium involves two hosts – the intermediate hosts which are most commonly pigs and harbor the larval stage, and the definitive host which are humans, sheltering the adult form. However, humans can become accidental intermediate hosts. The adults tapeworm enters the human body by eating the larval form present in the meat of the intermediate host.^[2]

A myriad of parasitic infections continue to pose health issues in tropical climates. In endemic countries, like India, cysticercosis is a common infection. The WHO experts in 2014, ranked T. solium as food borne parasite of greatest global concern.^[2] Cysticercosis can involve skin, subcutaneous tissue, muscles, intermuscular fascia, lymph nodes, brain, and various other organs.

Most subcutaneous cysticerci present as painless nodular or cystic swellings, that are easily amenable to fine needle aspiration. A definitive diagnosis of cysticercosis can be established by cytological examination and identification of the variable morphology in viable and degenerating/ calcified lesions. Microscopically, viable cysts demonstrates fragments of the bladder wall of the larva identified as loose granular fibrillary material, often thrown into rounded wavy folds with small round dark subcuticular or tegumental cells with small pyknotic nuclei, refractile claw shaped hooklets, and scolices, while degenerating lesions can demonstrate scattered hooklets and calcareous corpuscles.^[3,4] Background consists of inflammatory infiltrate comprising of eosinophils, polymorphs, histiocytes, and giant cell reaction.

Cysticercus cellulosae can regulate T-Cell response and interacts with the host immune system by excreting and secreting antigens, thereby escaping the host immune attacks and establish a persistent infection.^[5]

Serological tests and radiological investigations such as computed tomography scan and magnetic resonance imaging are also sensitive for diagnosing cysticercosis. Lentil lectin glycoprotein enzyme linked immunoelectrotransfer blot assay is the assay of choice for serodiagnosis.^[6]

Cysticercosis is an infection caused due to larval stage of the parasite T. solium. The clinical presentation is highly variable ranging from nodules occurring in the skin, subcutis, muscles, intermuscular fascia, and various other organs including the central nervous system. The index case emphasizes the awareness of possibility of parasitic infestation during the evaluation of isolated nodular and cystic swellings yielding fluidy or necrotic material on fine needle aspiration.

Filariasis is a vector borne public health issue and is endemic all over India. In India, W. bancrofti accounts for majority of the total filarial infections.^[1] Filarial nematodes can be detected in peripheral blood, body fluids, urine, sputum, lymph node, thyroid, parotid, scrotum, and subcutaneous tissues along with a wide variety of metastatic sites.^[2-4] Causative agents of human filariasis include W. bancrofti, B. malayi, Brugia timori, Loa loa, Mansonella perstans, Mansonella ozzardi, Mansonella streptocerca, and Onchocerca volvulus. Of all of the human filarial nematodes, W. bancrofti has the widest geographic distribution.^[5] The existence of filarial nematodes in association with metastatic deposits could be coincidental or may involve a different pathogenetic mechanisms. Filarial parasites exert profound immunoregulatory effects on the host immune system with both parasite-antigen specific and more generalized levels of immune modulation.^[6] The immune-modularity effects of microfilaria can be responsible for delayed post-operative healing after neck dissection.

Few authors have speculated that increased vascularity of the tissues and transmigration of microfilaria along with metastatic tumor emboli, decreased host immune response could be a possible reasons for lodgement of filarial in the metastatic sites.^[3,7,8]

This case highlights the importance of diligent screening of all cytology smears in endemic regions as the occurrence of microfilaria in cervical nodes of patients with oral cavity malignancy requiring neck dissection can have different implications in post-operative healing.

TB is a significant cause of high morbidity and mortality and is more common in developing countries. TB of the female genital tract is a rare disease and more commonly involves the upper genital tract (fallopian tubes and endometrium) as compared to lower genital tract.^[1,2] TB of cervix is very rare as the stratified squamous epithelium is resistant to the tubercular bacilli.^[3] Cervical TB accounts for 0.1–0.65% of all the TB cases and 5–24% of the genital tract TB cases.^[1,2] The incidence of TB is on rise.^[1] It can occur at any age but commonly affects women of reproductive age group.^[4,5] The two common organisms responsible for genital TB are M. tuberculosis or Mycobacterium bovis.^[1] Genital tract TB usually occurs from the hematogenous spread of infection from the primary focus. Cervical TB almost always occur secondary to TB of fallopian tube or endometrium and is typically associated with pulmonary TB.^[1,2] It can occur by either hematogenous spread, lymphatic spread, or by direct extension from the primary focus.^[1,6,7] Rarely, primary route can be the cause of infection introduced by the partner suffering from TB of genitourinary tract.^[2,4] Chowdhury suggested that sputum may also be source of infection when it is used as a sexual lubricant.^[4] The symptoms of genital TB can range from constitutional symptoms to infertility.^[1,2] The common presentations include abdominal pain, menstrual irregularities, discharge per vaginum, postmenopausal bleeding, etc.^[2] Grossly TB can present as papillary or vegetative growth, multiple tiny nodules or ulcer, and on imaging studies (hysterosalpingography or ultrasonography) of cervix, there can be seen diverticular outpouching of cervix with feathery appearance or cervical distortion etc.^[1,3] These features can be easily misinterpreted as cervical carcinoma.^[1] Microscopic examination of a cervical biopsy is characterized by well-formed epithelioid cell granulomas which may be associated with multinucleated Langhans type giant cell reaction and caseation necrosis. Lymphoplasmacytic infiltrates are seen at the rim of granulomas.^[2] TB of cervix needs to be differentiated from other granulomatous diseases, for example, lymphogranuloma venereum, sarcoidosis, schistosomiasis, amoebiasis, brucellosis, foreign body granuloma due to suture, crystal or cotton, and carcinoma cervix.^[2,8-11] The confirmation can be done by demonstration of acid fast bacilli of TB on ZN staining or isolation of mycobacterium.^[2] However, ZN stain and culture may be negative in one-third of the cases. In these cases, identification of typical granulomas is sufficient for the diagnosis of TB, if other causes of granulomatous cervicitis are excluded from the study.^[1,2] Newer diagnostic techniques such as enzyme linked immunosorbent assay or polymerase chain reaction may aid in the diagnosis of TB.^[8,9] The treatment includes anti tubercular therapy. The granulomas disappear after the treatment; however, fertility is low in patients even after the treatment due to subsequent healing by fibrosis and adhesions.^[4,5] The best method of preventing TB is Bacillus of Calmette Guerin vaccination and healthy lifestyle.^[5]

Genital TB is a chronic disease in females with low-grade symptoms. It commonly involves fallopian tubes and endometrium. Cervix is an uncommon location for genitourinary TB. The gross appearance and imaging studies of cervical TB may mislead as cervical carcinoma. Therefore, microscopic examination and positive ZN stain and culture are diagnostic. TB may lead to fibrosis and adhesion and is a major cause of infertility among females. Therefore, screening for genital TB must be a part while evaluating for the menstrual irregularities or infertility. Early diagnosis and further treatment are the key to avoid the complications associated with TB.

What is the most likely interpretation of FNA using the Milan system? [Figure 1a-c]

Non-neoplastic

c. Neoplasm: Benign.

FNA smears were cellular and showed benign-looking epithelial cells arranged in large cohesive sheets, clusters, and groups. They exhibit mild degenerative nuclear changes and abundant eosinophilic granular cytoplasm. Background showed abundant eosinophilic proteinaceous material along with a few neutrophils, lymphocytes, macrophages, and debris. There was no evidence of mitosis, necrosis, or atypia in the smears examined. To interpret and report the case, “The Milan System for Reporting Salivary Gland Cytopathology” was used; the cytomorphological features were suggestive of Category IV A – Benign Salivary Gland Neoplasm.

On inquiry, the patient showed a previous (3 months prior) USG report and fine-needle aspiration cytology (FNAC), which were done outside. The USG report was suggestive of a retention cyst and the FNAC was consistent with the radiological findings of a “Retention cyst.”

An excisional biopsy was performed after 12 days of FNAC. On the basis of gross and microscopic findings, what is the diagnosis? [Figure 2a-d]

Cystadenoma

e. Low-grade intraductal carcinoma.

There was no evidence of necrosis grossly. Multiple H&E stained sections examined under the microscope showed a salivary gland neoplasm consisting of solid and cystic areas. Cysts showed intracystic and intraductal proliferation of neoplastic epithelial cells arranged in papillary, micropapillary, and “pseudocribriform” architecture, displaying false punched out spaces and “Roman bridge” formation. The cysts cavities were filled with proteinaceous secretions. Tumor cells exhibit mild-to-moderate pleomorphism, vesicular chromatin, inconspicuous 1–2 nucleoli, and a moderate to abundant amount of eosinophilic cytoplasm. At places, a few cells showed apocrine changes. Myoepithelial cells were noted. Adjoining stroma showed areas of hemorrhage and lymphoid cell proliferation, well demarcated from normal salivary gland acini. Tiny foci of necrosis were identified; however, an invasion was not seen. Mitosis was exceedingly rare. No lymphovascular or perineural invasion was noted. Surgical margins were free of tumor cells. Four intraparotid lymph nodes identified microscopically showed features of reactive lymphoid hyperplasia.

To conclude the diagnosis, whole tissue was processed to screen for invasion, which was not identified on the total of 19 sections passed. Thereafter, a diagnosis of “Low-grade-Intraductal Carcinoma” was awarded. Immunohistochemistry (IHC) was performed by application of S100, which came out negative for tumor cells.

What is/are the diagnostic feature of low-grade intraductal carcinoma?

“Pseudocribriform” architecture displaying false punched-out spaces and “Roman bridge” formation without invasion

a. “Pseudocribriform” architecture displaying false punched-out spaces and “Roman bridge” formation without invasion.

What are the major pitfalls observed in the cytohistomorphological correlation of this case?

Gross aspiration of thick yellow fluid, followed by slight reduction of size of the swelling

e. All of the above.

This case was mislabeled as a retention cyst on USG and was unrecognized and under-diagnosed on FNAC done outside in a private laboratory despite being an extremely rare entity. On both occasions, FNA procedures done outside as well as in our department yielded similar fluidy aspirates [Table 1].

Although making a definite diagnosis of this tumor on FNA smears is challenging, at least can be suggested as salivary gland neoplasm. The Category IV A, B, and C of Milan’s system is highly overlapping. The presence of above-mentioned cytomorphological findings is of a salivary gland multicystic neoplasm; however, exact diagnosis is almost impossible. However, raising the diagnostic possibility of salivary gland neoplasm rather than just a cyst in a pre-operative FNA would be of great help to the surgeon so that the complete resection was planned. The distinguished nomenclature relies solely on histopathological examination of stromal invasion that cannot be evaluated on pure cytological grounds.

Warthin’s tumor was one of the differential diagnoses considered due to the classical background (consisting of few lymphocytes) and cystic nature of the tumor, as well as the few oncocytic looking cells; however, the florid lymphoid background was absent in our case. The lymphocytic background is sometimes very misleading, as in the present case, as hitting an intrasalivary gland lymph node gives a similar picture on a smear, even when associated with oncocytic looking cells.

What are the most obvious biopsy findings describing the present case’s prognosis?

Cystic areas

d. Negative surgical margins and absence of stromal invasion.

Low-grade intraductal carcinoma (LG-IC) is a rare salivary gland malignant tumor.^[1] To the best of our knowledge, only 56 cases have been reported in the archives to date. The United States accounts for half of all reported cases, followed by Japan (26%), Canada, China, Korea, Taiwan, Czech Republic, and Italy.^[1-5] So far, only one case has been documented in India as an incidental diagnosis on an excision biopsy of a 56-year-old female, who was clinically and radiologically diagnosed with a pleomorphic adenoma of the palate.^[6]

In 1996, Delgado et al.,^[7] mentioned LG-ICs for the first time in a case series, where it was described as a “mass forming lesion with morphological features analogous to mammary ductal hyperplasia and intact myoepithelial cell layer.” Since then, the nomenclature of LG-IC has been reviewed at times. It was renamed from “Low-grade cribriform cystadenocarcinoma” or “Low-grade salivary duct carcinoma” to “Salivary duct carcinoma in situ” in 2005.^[8,9] In 2017, the World Health Organization Head and Neck tumors reclassified the entities LGCCC and salivary duct carcinoma in situ collectively as “Intraductal carcinoma,” with low-grade and high-grade features, respectively.^[10-12]

In the majority of cases, LG-ICs are seen in a wider age range of 27–93 years, with a slight female (M: F = 1:1.3) predilection.^[2-5] The most common site is the parotid gland (>80%), with rare occurrences in minor salivary glands. The clinical presentation of LG-IC is mostly a circumscribed cystic mass with indolent behavior. Exceptionally, LGIC can be intranodal, having arisen from salivary gland inclusions in the lymph node. Macroscopically, LG-ICs are well-circumscribed, non-encapsulated, multicystic lesions; a size varying from 0.7 to 5.3 cm, and contain serous to hemorrhagic fluid.^[1] Histologically, following variants have been described:

Intercalated duct-like (most common)^[13]

Complete surgical excision with preservation of the facial nerve is the most commonly practiced management at present. LG-IC has an excellent prognosis after complete excision, with no metastasis or mortality at a follow-up of 2–12 years, regardless of nuclear grade. However, recurrence can occur as a result of incomplete resection, positive surgical margins, or metastasis. The previous systemic reviews illustrate that adjuvant radiotherapy is not justified for tumor resections with negative margins, even in the presence of a close margin. However, it may be advised in cases of positive margins or invasive tumors.^[1]

A systematic review performed by Giovacchini et al.^[1] revealed the heterogeneous morphology of tumor cells lacking cellular or nuclear pleomorphism, prominent nucleoli, significant mitotic activity, and necrosis. Furthermore, these tumors had no local or perineural invasion.^[1,2,7,15]

Nakazawa et al.,^[4] Jeong et al.,^[16] and Kokabu et al.,^[17] showed FNA reports suggestive of a cystic lesion with a mildly irregularly shaped nucleus with inconspicuous nucleoli and little atypia; some had single, large, and clear cytoplasmatic vacuoles. Background showed scattered lymphocytes, neutrophils, macrophages, and eosinophils. The FNA morphology is closely similar to our case findings with specific backgrounds.

Kuo et al.^[18] identified the following LG-IC multicystic architecture differential diagnoses: cystadenocarcinoma, cystadenoma, salivary duct carcinoma in situ/high-grade intraductal carcinoma, conventional salivary duct carcinoma, acinic cell carcinoma (Papillary Cystic Pattern), mammary analog secretory carcinoma, sclerosing polycystic adenosis, ductal adenoma with striated duct differentiation, and intercalated duct lesion.

According to the literature, FNAC has lower sensitivity to cliché the diagnosis of LG-IC as malignant, with only four FNAs out of all cases reported to date showing malignant neoplasms,^[11,17,19] 23% of cases reported as benign,^[12,20,21] and 46% of cases reported as SUMP.^[3-5,17,22]

Immunohistochemically, Giovacchini et al.^[1] reviewed that total 55 cases revealed that 92% cases showed tumor cells positive for S-100, 18% for cytokeratinAE-1/AE-3, 14.5% for mammaglobin, 67% for GCDFP-15, 94% for calponin, 86% for DOG1, 91% for CK14, 95% for SMA, 70% for CEA, and 11% for CK7. Instead, 95% of tumor cells were negative for Her-2/neu, 62% for androgen receptor, 90% for ER, 90% for PR, and 75% for p53. In LG-IC, GATA-3 was generally negative; it may be useful in distinguishing LG-IC from mammary secretory carcinoma, metastatic squamous cell carcinoma, mucoepidermoid carcinoma, salivary duct carcinoma, and Warthin tumor, which are usually positive.^[23] The role of IHC is found to be supportive, however not specific, as well as controversial in the diagnosis for LG-IC.

LG-ICs are unique in their cytohistomorphological complexity. On histomorphology, they have classical non-invasive pseudocribriform and Roman bridges-like architectural patterns, which are similar to the pattern seen in low-grade intraductal breast carcinoma. This specific tumor is considered the counterpart of low-grade intraductal breast carcinoma, which is highly debatable and still not confirmed. On FNAC, the overlapping cytomorphological features make its identification as a malignant tumor more difficult. FNAC plays a pivotal role in detecting both benign and malignant etiologies, the latter in those not suitable for attempted curative surgery or with recurrent disease before palliative treatment, and can also reduce the rate of salivary gland surgery by one-half to one-third. The crux of the case reported is the importance of FNA with good skills to identify neoplastic etiology, especially indolent malignant tumors like LG-IC when cytomorphological features are benign-looking. However, histopathological examination is considered the “gold standard” to arrest the diagnosis of LG-ICs, and after complete excision, it carries an excellent prognosis.