Tehran University of Medical Sciences Iranian Journal of Parasitology 1735-7020 10 1 2015 03 15 132 135 EN Zohreh Andalib Aliabady Department of Parasitology and Mycology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran. Fariba Berenji Department of Parasitology and Mycology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran. Mahmoud Reza Jamshidi Department of Parasitology and Mycology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran. 2015 10 14   Hydatid cyst is an important endemic zoonosis in Iran. It may be seen in various organs of body. Musculoskeletal system is rarely involved by hydatid cyst, the larval form of Echinococcus granulosus. On clinical basis, it may resemble any soft tissue tu-mor. A 70-years old housewife living in Ardoghesh, a village in Neyshabur, north-east Iran, was admitted to general surgery clinic because of a painless mass in the back of her left thigh. This case emphasizes that hydatidosis should be included in differential diagnosis of any soft tissue mass especially in regions where hydatidosis is endemic. https://ijpa.tums.ac.ir/index.php/ijpa/article/view/341 https://ijpa.tums.ac.ir/index.php/ijpa/article/download/341/434