Utility and diagnostic accuracy of endobronchial ultrasound-guided transbronchial fine-needle aspiration cytology of mediastinal lesions: Saudi Arabian experience

INTRODUCTION

Although mediastinoscopy and video-assisted thoracoscopy have been the primary diagnostic techniques for obtaining samples of any suspicious lesions on imaging, particularly in the mediastinum, minimally invasive techniques like endobronchial ultrasound-guided transbronchial fine-needle aspiration (EBUS-TFNA) have gained popularity because of the ability to obtain tissue with less potential complications. It is a relatively new procedure for sampling mediastinal and hilar lymph nodes.[1234] This procedure enables direct and real-time aspiration of the mediastinal and hilar lymph nodes and is a less invasive alternative to mediastinoscopy.[5]

Endobronchial ultrasound-TFNA using a novel endobronchoscope with needle has been noted to have higher yields than those typically associated with conventional TBNA (85% vs. 66%).[678] Some of the early studies on conventional TBNA; however, did not use on-site evaluation of adequacy of the specimens,[9] which may have improved the sensitivity of the procedure by increasing the rate of adequate specimens.[1011]

The diagnostic yield of EBUS-TFNA procedure is better compared with conventional transbronchial needle aspiration because of the ability to observe the needle in the target of interest, and it has been demonstrated that the reproducibility of the diagnosis is excellent in experienced hands.[11213] In addition, EBUS-TFNA allows for broader access to mediastinal lymph nodes than mediastinoscopy.[12131415]

Several types of specimens can be obtained with EBUS guidance, including needle aspiration, brushing, washing, lavage, and core needle biopsy.[12416] Direct smears can be made from needle aspiration and brushing specimens to allow on-site evaluation. The other materials are usually processed in the cytology laboratory and subsequently, evaluated by the cytology personnel. Shidham's method can be applied to the remaining cytology specimen to improve the quality of diagnostic material in cell block sections.[17]

These cytological materials provide vital diagnostic information for appropriate patient management. In the English literature, only few studies have investigated the cytological features of EBUS-TFNA specimens.[12416] The objective of this study was to review the diagnostic utility of EBUS-TFNA specimens from a cytological perspective, in addition to correlate these findings with the histological follow-up.

MATERIALS AND METHODS

We performed a computerized search of the cytopathology electronic database from our institution for all aspirations performed by EBUS-TFNA from May 1, 2010 to December 15, 2013 for a variety of clinical indications. Procedure conducted by one experienced pulmonologist in the bronchoscopy suite on all patients with mediastinal lymphadenopathy based on chest computed tomography (CT). All patients understood the procedure required to establish the diagnosis, and written informed consent form was obtained from all participants. Local anesthesia with mild conscious sedation was used for the procedure.

Endobronchial ultrasonography was performed using fiberoptic ultrasound bronchoscope with a linear scanning probe (BF-UC260FW, Olympus Medical System, Tokyo, Japan). A dedicated ultrasound scanner (ALOKA SSD-Alpha 10, ALOKA Ultrasound System, Japan) was used for image processing. Targeted lymph node was sequentially sampled with a dedicated 21-gauge needle (NA-201SX-4021, Olympus Medical System, Tokyo, Japan).

Smears were made at the bedside in the bronchoscopy suite.

RESULTS

This study included a total of 80 EBUS-TFNA specimens obtained from 50 males (62.5%) and 30 females (37.5%). The male: Female was 1.6:1. The patients’ age ranged from 16 to 80 years old with a mean age of 46.5 years. Of the 80 consecutive cases, 73 (91.2%) had lymph node sampling, three had lung sampling and five had mediastinal mass sampling.

The cytological diagnosis included 15 cases (18.75%) positive for malignancy, 48 cases (60%), negative for malignancy and 17 cases (21.25%) unsatisfactory/nondiagnostic as shown in Table 1. Of the 48 cases which were negative for malignancy, 24 (50%) cases were granulomatous inflammation [Figure 1]. Of the 15 cases with a positive diagnosis, there were five (33.3%) nonsmall cell carcinoma [Figure 2], three (20%) nonHodgkin's lymphoma [Figure 3], one (6.6%) small cell carcinoma [Figure 4], one (6.6%) neuroendocrine carcinoma, one (6.6%) poorly differentiated carcinoma and three (20%) nonpulmonary metastatic carcinoma (one upper gastrointestinal tract [Figure 5], nasopharynx [Figure 6], and one poorly differentiated carcinoma with unknown primary).

Table 1 Summary of cytological diagnosis in 80 EBUS cases

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Figure 1

Granulomatous inflammation, cytology smear shows well-defined epithelioid cell granuloma (diff-quick stain, original magnification ×500)

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Figure 2

Cytology smear from lung adenocarcinoma metastatic into mediastinal lymph node (Papanicolau stain, original magnification ×500)

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Figure 3

NonHodgkin's lymphoma, cell block preparation obtained from mediastinal lymph node by endobronchial ultrasound-fine needle aspiration (Hematoxylin and Eosin stain, original magnification ×400)

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Figure 4

Cytology smear from small cell carcinoma of lung primary, metastatic into mediastinal lymph (diff quick stain, original magnification ×500)

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Figure 5

Cytology smear from mediastinal lymph node reveals metastatic Adenocarcinoma of gastric origin (Papanicolau stain, original magnification ×500)

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Figure 6

Cytology smear from mediastinal lymph node reveals metastatic nasopharyngeal carcinoma (Papanicolau stain, original magnification ×500)

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The overall diagnostic yield of our EBUS-TFNA specimen was 78.75% with 17 cases, which were considered unsatisfactory.

Histological correlation

Forty-seven cases (58.75%) of 80 cases had corresponding core biopsies or follow-up surgeries. Of the 17 unsatisfactory specimens on EBUS-TFNA, 15 cases had corresponding histopathology follow-up. Of these cases on histology, six cases were negative, two unsatisfactory, two cases of granulomas (TB), three cases were of adenocarcinoma, one case of Hodgkin's lymphoma, nodular sclerosis subtype and one case of leiomyoma. Of the 24 negative cases, 14 cases had corresponding histology follow-up. Of these, nine cases were negative, three cases of granulomatous inflammation (two TB and one sarcoidosis), one case of adenocarcinoma and one Hodgkin's lymphoma. Of the 24 cases of granulomatous inflammation diagnosed on EBUS-TFNA, 12 had corresponding histology confirmation. 10 cases were granulomatous inflammation (seven sarcoidosis and three TB) and two were negative for granuloma or malignancy. Of the 15 cases of malignancy, six cases had corresponding histologic follow-up. Of these five cases were malignant (two were adenocarcinoma, one synovial sarcoma, one non-Hodgkin's lymphoma and one metastatic adenocarcinoma from upper gastrointestinal tract) and one case was negative. This data is summarized in Table 2.

Table 2 Cytologic-histological correlation in EBUS guided fine-needle aspiration biopsy

Thus, in our study, 32 cases (68%) had the same cytological and histological diagnosis and 15 cases (31%) had cytological diagnosis with discordant histological diagnosis. This data is summarized in Table 3.

Table 3 Cytological cases with discordant histological diagnosis

When the histological diagnosis was taken as the gold standard, the sensitivity, specificity, positive predictive value, and negative predictive values for diagnosing granulomas by EBUS-TFNA are 77%, 82%, 83%, and 75% and for diagnosing malignancy are 71%, 100%, 100%, and 82%, respectively.

DISCUSSION

The investigation for mediastinal masses or nodular lesions etiology is a subject that the clinicians are commonly faced with. However, the detection of enlarged mediastinal lymphadenopathy and accurate staging of extrathoracic malignancy is important to plan further treatment. Mediastinoscopy is considered the gold standard procedure in this clinical scenario. However, it requires general anesthesia, and there is the possibility of significant complications.[18] In addition, mediastinoscopy has limitations in accessing hilar nodal stations, can be difficult in patients of previous radiations and the procedure cannot be repeatedly used on the same patient.[19]

There are various fine-needle aspiration techniques exist for diagnosing lung and mediastinal lesions, including trans-esophageal EUS-FNA, CT-guided transthoracic FNA, conventional TBNA, and EBUS-TFNA. Among them, EBUS-TFNA is a relatively new modality for sampling mediastinal lesions. It has been shown to be a safer, more sensitive, and cost-effective diagnostic procedure, which shows potential to avoid explorative thoracoscopies.[1234122021] It is usually performed under local anesthesia, using moderate sedation in an outpatient setting.

There are a few studies published regarding the clinical usefulness of EBUS-TFNA from the United States,[22] specialized centers in Europe, the United Kingdom and Japan.[71523] These studies showed high diagnostic rates for EBUS-TFNA with sensitivities and positive predictive values of more than 90% and specificities of 100%.

The present retrospective study from Saudi Arabia showed that EBUS-TFNA is a sensitive, accurate and safe modality for the evaluation of mediastinal masses and nodular lesions. EBUS-TFNA was introduced in recent years to the pulmonology and thoracic surgery practice in our hospital as a new modality to diagnose and stage lung cancer and to evaluate mediastinal diseases. In our study, diagnostic material was obtained in 78.5% of sites sampled (63/80). The unsatisfactory specimen rate was 21% (17/80). An accurate diagnosis was made in 32 (68%) of 47 satisfactory aspirates with histological follow-up. The sensitivity, specificity, and positive and negative predictive values for diagnosing granulomas by EBUS-TFNA were 77%, 82%, 83%, and 75% and for diagnosing malignancy are 71%, 100%, 100%, and 82%, respectively. This number is slightly lower than other retrospective studies who reported sensitivity of EBUS-TFNA between 85% and 92%, respectively.[234212224252627]

Alsharif et al. have reported a study of 100 patients who underwent EBUS-TFNA, a nondiagnostic rate of 15.7%.[4] In their study, 28% of cytology specimens had corresponding histology, yielding sensitivity and specificity of 86% and 100%, respectively. Jacob-Ampuero et al. reported 48 cases with a diagnostic yield of 77% and both sensitivity and specificity of 100%.[2] Feller-Kopman et al. have reported a study of 135 cases of lymph node and lung lesion biopsy by EBUS-TFNA with sensitivity and specificity of 85% and 100%.[26] The overall nondiagnostic rate reported by most authors range from 4% to 23%.[2426] Our data shows nondiagnostic rate of 21.25%. There are various factors, which contribute to the diagnostic yield. Some of them are skill of the endoscopist, size and station of the lymph nodes, difficult target with fibrotic tissue and experience of the cytopathology personnel performing on site material adequacy.

Until date, pathology criteria for representativeness of an aspirate are not well-established for EBUS-TFNA and may vary among pathologists.[1] There has been little focus on this area and definition of adequacy can be improved by setting up commonly agreed pathology criteria. The cellularity plays an important role in making the diagnosis. For our study, we found that the cellularity varied widely and the adequate sample was defined as the presence of either site specific diagnostic material or sufficient lymphoid cells with at least 40 lymphocytes per high power field in the most cellular areas, as is used in other studies.[2829] The amount of lymphoid tissue is likely not only dependent on the bronchoscopist's skill, but also on the degree of nodal involvement by the disease process, particularly in metastatic lesions or granuloma. Therefore, the lymphoid tissue may not be seen in a lymph node that has been entirely replaced by granulomata or metastasis. When there are very few lymphocytes, they most likely come from peripheral blood rather than a lymph node. We consider that the presence of moderate to abundant numbers of lymphocytes and/or pigmented macrophages is a good indicator of adequate sampling of lymph node and lung parenchyma in most cases. Hence, as the cytopathological adequacy criteria for EBUS-TFNA are not well-established, future studies are needed to help standardize these criteria because of its importance in maximizing the diagnostic performance of the procedure and defining an adequate specimen, which can minimize false-negative diagnoses.

An early study by Baker et al.[9] have reported a significant difference in the predictive values of negative transbronchial aspirates with and without lymphocytes (78% vs. 36%). Later Alsharif et al.[4] found that the presence and quantity of bronchial cells had no bearing on the adequacy because these cells were found in the majority of their samples, without correlation with the number of lymphocytes. Excess contamination with normal cells can obscure the scant malignant cells or, in cases with reactive respiratory cells, mimic a well-differentiated adenocarcinoma. The cell block is extremely helpful in such cases and immunohistochemical analysis can be performed when necessary.

SUMMARY

Endobronchial ultrasound- TFNA is minimally invasive, cost-effective, accurate, safe, and promising technique for the diagnosis of mediastinal masse/lesions. It is usually performed under local anesthesia, using moderate sedation in an outpatient setting. It has a good sensitivity and high specificity with a high diagnostic yield. Cell block for histology and immunohistochemistry provides supportive evidence for the diagnosis. The optimum use of EBUS-TFNA depends on the effective collaboration between the cytotechnologist, pathologist and the bronchoscopist.

COMPETING INTERESTS STATEMENT BY ALL AUTHORS

Declare that we have no competing interests. The authors would like to emphasize that we have not currently or in the past received financial or any other form of support from any of the companies and/or manufacturers mentioned in the article.

AUTHORSHIP STATEMENT BY ALL AUTHORS

All authors of this article; utility and diagnostic accuracy of endobronchial ultrasound-guided transbronchial fine-needle aspiration cytology: Saudi Arabian experience. Declare that we qualify for authorship as defined by ICMJE. Each author has participated sufficiently in the work and takes public responsibility for appropriate portions of the content of this article. AB carried out the molecular genetic studies, participated in the sequence alignment and drafted the manuscript. JY carried out the immunoassays. MT participated in the sequence alignment. ES participated in the design of the study and performed the statistical analysis. FG conceived of the study, and participated in its design and coordination and helped to draft the manuscript. All authors read and approved the final manuscript. Each author acknowledges that this final version was read and approved.

ETHICS STATEMENT BY ALL AUTHORS

This study was conducted with approval from Institutional Review Board (IRB) of King Khalid University Hospital, King Saud University, Riyadh, Saudi Arabia. Author takes responsibility to maintain relevant documentation in this respect.

EDITORIAL/PEER-REVIEW STATEMENT

To ensure the integrity and highest quality of CytoJournal publications, the review process of this manuscript was conducted under a double blind model (authors are blinded for reviewers and vice versa) through automatic online system.