Isolated muscle involvement in hydatid cyst.

Although hydatid cyst, caused by Echinococcus granulosus, can develop in any part of the body, involvement of the liver and lung represents approximately 90% of all cases. Involvement of the musculoskeletal system is comparatively rare. Diagnosis is difficult because symptoms are non-specific. We present a case, together with the imaging findings, in order to draw attention to the exclusion of hydatid cyst before surgery or biopsy in patients with muscular pain and a palpable mass.