Atypical Pectoralis Major Muscle Wasting in a Recreational Weight Lifter.

Pectoralis major injuries are relatively uncommon and can pose a diagnostic challenge. Deformity and weakness of this muscle in weight lifters is typically due to traumatic tendon rupture and often requires surgical repair. However, there are other less common etiologies that can mimic the clinical presentation of pectoralis major wasting and weakness that require different treatment approaches. This article describes a case of a 48-year-old recreational weight lifter who presented with severe pectoralis major wasting and weakness secondary to isolated mononeuropathy of the lateral pectoral nerve possibly due to Parsonage Turner syndrome. The patient was treated nonoperatively and achieved full recovery 18 months after onset. Parsonage Turner syndrome should be included in the differential diagnosis of patients with atraumatic weakness and wasting of the pectoralis major muscle and dysfunction. [Orthopedics. 2016; 39(4):e756-e759.].