Case report

Rationale: Focal myositis (FM) is a very rare myopathy of unknown etiology characterized by focal enlargement within one single skeletal muscle. In particular, it occurs only involving the Sartorius muscle has never been reported. Patient concerns: A 25-year-old man was admitted to the hospital with progressive restricted left hip joint extension, left thigh discomfort and gait disturbance for 6 years. Diagnoses: Combining clinical manifestations with results of radiological and pathological examinations, it was consistent with the diagnosis of FM Interventions: The patient received a surgery under general anesthesia to release the contracted Sartorius tendon. Outcomes: The range of motion of the patient's left hip and ipsilateral knee has significantly improved as well as the discomfort of his left thigh relieved obviously after the surgery. Lessons: This case report is the first to report FM presenting as sartorius muscle contracture and the surgery is an alternative therapy for these patients.