Clinicopathological study of subcutaneous heminthicnodules: Unusual sites and diagnostic dilemmas

Superficial palpable swellings with helmintic infection as an underlying etiology is usually an accidental finding in the surgically excised specimens. Somatic nematodes and cestodes are the commonly implicated organisms, and the zoonotic nematodes show an emerging trend. The present study aims to reappraise the histopathological findings of helminthic etiology in superficial swellings which were clinically suspected to be of neoplastic/non neoplastic nature. Thirty six cases of palpable superficial nodules with infective etiology over a period of five years were reviewed. 19/36 were of helminthic etiology were included in the present study. Pertinent demographic and clinical data were retrieved from the medical archives. Amongst the 19 cases, 8 were males and 11 females. Chest wall (4/19), and eyelids (3/19) were the most common sites involved. The size ranged from 0.8-15 cm in greatest dimension. Presence of histiocytes (13/19), granulomas (11/19), eosinophils (10/19), and giant cells (9/19) were the most consistent histological findings. 14 cases had discernible parasite morphology with diagnosis of filarial worms (7/19), Dirofilaria (3/19), cysticercosis (4/19), and hydatid cyst (1/19). Four cases had dead and calcified parasites with no discernible morphology. Granulomatous inflammation and tissue eosinophilia are strong indicators of a parasitic etiology. Subcutaneous and intramuscular filariasis, cysticercosis and hydatid cyst are well documented etoiologies whereas Dirofilariasis is an emerging zoonotic infection with worldwide case reports. Imaging techniques and fine needle aspiration can point towards the diagnosis; however in the absence of characteristic features, histopathology can be relied upon to diagnose a helminthic etiology.