A rare cause of insidious shoulder pain in a young female: A soft tissue aneurysmal bone cyst in supraspinatus muscle

Aneurysmal bone cyst (ABC) is an expansile cystic lesion which may affect any bone of the skeleton. Although extremely rare, lesions with histomorphological characteristics of an ABC occur in the soft tissue. Herein, we report the first case of ABC involving the supraspinatus muscle and mimicking common pathologies, such as myofascial pain syndrome or subacromial impingement syndrome.