Primary echinococcal cyst in the thyroid gland: a case report from Iran

Hydatid disease is prevalent in most sheep-raising countries in Asia, Australia, and eastern and southern Europe. Hydatid disease caused by Echinococcus granulosus is often manifested by a slow-growing cyst mass. Hydatid cysts may be found in almost every part of the body; however the lungs and liver are the most involved locations. Due to the vital cycle of the parasite, the thyroid gland is an uncommon site of infection even in the countries where the disease is endemic. Hydatic origin is suspected in only 50% of patients preoperatively and immunologic testing has a 33% false positive rate; therefore, hydatid cyst is more commonly considered intra-operatively and confirmed by a frozen section histology. This study reports a case of primary hydatid disease of the thyroid.