Solitary hydatid cyst of the thigh: a challenging diagnosis.

A 53-year-old woman presented with an enlarging mass in the medial aspect of her right thigh. Magnetic resonance imaging suggested an intramuscular hydatid cyst. The cyst was surgically excised. Although muscular hydatidinosis is rare, its resemblance to soft tissue tumors warrants careful diagnosis since any invasive diagnostic measures may lead to fatal complications.