Hydatid cyst of trapezius muscle: an unusual localisation. Report of a case and review of the literature.

The muscular localisation of hydatid cyst is very uncommon. The authors report a recently observed case of hydatid cyst of the trapezius muscle. An 81-year-old man presented with a 9-months history of a slow-growing painless mass in his left shoulder associated with itching. US examination showed a large multiloculated cystic mass, strongly suspicious of a hydatid cyst. At operation, under local anesthesia, complete surgical resection of the cystic mass was performed. The patient tolerated surgery very well. The postoperative course was uneventful and the patient was discharged from hospital on postoperative day 2. No recurrence occurred after 11 months. Muscular hydatidosis is very rare and can cause a variety of diagnostic problems, especially in the absence of typical radiological findings. The possibility of hydatid disease should always be kept in mind in the differential diagnosis of muscular masses, especially in endemic areas