Coexistence of microfilaria and chronic lymphocytic thyroiditis: a rare case report

Filariasis is a common health problem in tropical countries of Southeast Asia. The commonest site of involvement is the lymphatic system where the adult worms can remain viable for long periods. Though the patients can remain asymptomatic, the clinical presentation with hydrocele, fever, localised swelling and/or lymphedema are commonly seen. Localization of the parasite at various other sites like breast, lungs, and thyroid have been uncommonly described. We report a case of an elderly female who presented with a large anterior neck mass associated with a recent history of change in voice. Radiological investigations revealed a soft tissue mass in the neck along with multiple lesions in the thyroid which were suspicious of malignancy. Fine needle aspiration cytology, however, revealed microfilariae coexisting with chronic lymphocytic thyroiditis. This case highlights the importance of critical screening of cytology smears to identify the parasites at unusual locations. A correct diagnosis on a simple and inexpensive investigation like fine needle aspiration cytology can help in administering appropriate therapy at the earliest and avoiding unnecessary interventions.