Solitary hydatid cyst in thigh without any detectable primary site

Echinococcus granulosus causes a zoonotic infection called Cystic Echinococcosis (CE). Surgeons meet with hydatid cysts of the liver and lungs with reasonable frequency. However hydatid cyst may also appear in other parts of the body. A 30 years old lady presented with a smooth slow-growing subcutaneous nodule on the anteromedial side of the right thigh with no detectable primary site in the liver or lung. The case was subsequently diagnosed as hydatid cyst of muscle and radical surgery was done under coverage of anihelminthic drug. The common practice in this type of case is to do fine needle aspiration cytology (FNAC) taking the lesion to be a soft tissue neoplasm. The aim of this case presentation is to be aware of that in case of a diffuse non-tender swelling with history of gradual increase in size, hydatid cyst should be considered in the differential diagnosis.