An extrahepatic hydatid cyst with the fat-fluid level.

A hydatic cyst is a zoonosis caused by the larva of a tapeworm Echinococcus granulosus . The liver is the most commonly affected organ. Soft tissue localization has been reported in 2.3% of cases. Herein, we present a patient with a fat-containing hydatid cyst located in the left thigh. There are only a few reports in the literature on the presence of the fat-fluid level within a hydatid cyst. Previous studies have suggested that fat-containing hydatid cysts occur due to their cysto-biliary communication in the liver. In our case, we describe a fat-containing hydatid cyst in the extrahepatic location and discuss the pathophysiologic mechanism of fat inside it.