Primary echinococcal cyst in Trapezius muscle: An unusual intermuscular hydatidosis and review of literature.

The primary hydatid disease in musculoskeletal position is not common, but maybe present in endemic areas. The human being is always an accidental host. We reported a 30 years adult male patient with trapezius muscle primary hydatidosis. He admitted with a complaint of large swelling right upper back for 2 years. The clinical diagnosis was a lipoma, but ultrasound suggested cystic changes in soft tissue tumor or lipoma and FNAC was inconclusive. Finally, the MRI report revealed hydatid cyst disease and diagnosis become clear with intraoperative findings as well as histopathology reports. We are reporting this case to show the very rare location of primary echinococcal cyst in trapezius muscle and challenging approach to diagnose this case with basic investigation.