Hydatid cyst of the infraspinatus muscle.

Muscle hydatidosis is rare accounting only for 3%-5% of cases. Until now, only one case of muscular hydatidosis involving the infraspinatus muscle has been recorded. Hereby, we present a case report of primary hydatidosis of infraspinatus muscle in a 32-year-old woman from Central India who presented with painful soft-tissue swelling. Ultrasonography appearance was consistent with that of hydatid cyst; while serology was negative, pericystectomy was performed, and the diagnosis was confirmed. The patient was followed up for a period of 6 months, and no recurrence was noted. Hydatid cysts should be considered in the differential diagnosis of soft-tissue swellings, particularly in endemic regions.