63-year-old man with right biceps and right pectoralis major abscesses: an unusual case of pyomyositis.

Pyomyositis is considered a great mimicker and masquerader. This case is of a 63-year-old man with diabetes who initially presented to the outpatient clinic afebrile with right shoulder pain. His work-up was negative, and he was discharged home. He subsequently presented to the emergency room (ER) two times for worsening right shoulder pain. During his first visit to the ER, his work-up was unremarkable, and he was discharged home. On his return to the ER, he was now febrile with inflammation involving his right upper extremity and right chest wall. Imaging studies of his right upper extremity and his right chest wall were consistent with multiple abscesses. Methicillin resistant Staphylococcus aureus was cultured from the abscess, and from blood and urine cultures. The diagnosis of pyomyositis was confirmed. This case illustrates the difficulty of diagnosing pyomyositis and the importance of including it in the differential diagnosis, especially in an immunocompromised patient.