Inguinal swelling in a young female: An unusual finding

ANSWER

The correct cytological interpretation is b. Cysticercosis.

EXPLANATION

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.

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Figure 2:

Microphotograph panel of smears (a and b) showing large fragments of bladder wall in a background of dense inflammatory infiltrate (c and d) fibrillary bluish material woven into rounded multiple subcuticular cells with interspersed tiny blue pyknotic nuclei surrounded by dense inflammatory infiltrate. (a-c: ×10, d: ×40) (MGG).

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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.

ADDITIONAL QUIZ QUESTIONS

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

1. Feco-oral contamination

2. Droplet transmission

3. Inhalation

4. Sexual contact.

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

1. Cysticercosis is caused by larval stage of T. solium

2. Humans cannot be both definitive and intermediate hosts

3. Inflammatory response is usually associated with cysticercosis

4. Viable cysticerci can persist for several months to years in humans.

ANSWERS TO THE ADDITIONAL QUIZ QUESTIONS

Answers: Q2-a, Q3-b.

EXPLANATION FOR ADDITIONAL QUIZ QUESTIONS

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]

BRIEF REVIEW OF THE TOPIC

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]

SUMMARY

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.