Hydatid Cyst of Thyroid Gland: A Case Report

Hydatid cysts in the thyroid gland are extremely rare, even in endemic areas. A 64-year-old male presented with a painless swelling on the left side of the thyroid swelling for 2 years. Ultrasonography revealed a large multiloculated anechoic lesion while fine needle aspiration cytology yielded clear watery to granular fluid containing hooklets, protoscolioces, laminated membrane, identifiable on both Giemsa stained and unstained slides. Further tests confirmed positive serology for Echinococcus, and computed tomography (CT) scan showed no such cysts in other organs. The patient was treated successfully with a lobectomy without signs of recurrence in 1 year. Although primary hydatid cysts of the thyroid are rare, even in endemic areas, they should be considered as a differential diagnosis when evaluating thyroid nodules in these regions. Fine needle aspiration cytology (FNAC) can confirm the diagnosis. However, clinicians must take care to avoid anaphylactic reactions. The use of FNAC in hydatid disease is debatable as it may cause anaphylactic reaction, but in cases with doubtful diagnosis, it can serve as a confirmatory tool. The condition can be managed successfully with lobectomy.