An Unusual Cause of Insidious Back and Shoulder Pain in a Man: A Case Report.

Hydatid cyst is an infestation caused by Echinococcus granulosus , which is endemic in most countries and most commonly affects the liver and lungs. Isolated muscle involvement is very rare and accounts for 3-5% of all cases. In April 2022, Health Sciences University Elaziğ Fethi Sekin City and Research Hospital in Turkey received a referral for a 37-year-old male patient from the physical therapy and rehabilitation outpatient clinic. The patient presented with complaints of chronic pain in his left shoulder and back, which worsened with movement. After the radiological and serological confirmation of diagnosis, the patient underwent wide surgical resection, adjuvant and neoadjuvant anthelmintic chemotherapy. Precise and complete removal of the cyst without infecting the surrounding tissues combined with anthelmintic chemotherapy will not only increase the success of the surgery but will also minimize the possibility of recurrence and distant organ spread. In this study, we aimed to raise awareness by presenting the first reported isolated hydatid cyst in the infraspinatus muscle case from our country, which is extremely rare.