Primary hydatidosis of the gracilis muscle in a girl.

Primary muscle hydatidosis is very rare. Rupture and spreading of the cyst contents by improper handling may later cause secondary cyst or allergic reactions. Preoperative recognition of a hydatid cyst is therefore critical. It often presents as a soft-tissue mass, however, and pre-operative recognition of this rare entity is clearly difficult. Here, a case of primary hydatidosis affecting the gracilis muscle is presented, and the magnetic resonance imaging, clinical and pathological findings are described.