Upper Arm Swelling - Football

HISTORY: A 19-year-old college football offensive lineman presented with several weeks of left shoulder fullness and anterior upper arm swelling. He had previously undergone left pectoralis major tendon repair following traumatic rupture over a year ago. He reported mild pain over the swelling and left biceps. There was no new injury, and he was playing with no deficit in strength or range of motion. Overall, he felt well and denied any fever, chills, or joint pain. PHYSICAL EXAMINATION: A tender localized area of anterior swelling was noted over the proximal left upper arm. The area had no fluctuance, warmth, or erythema. There was full active range of motion and normal strength of the left shoulder including deltoid, rotator cuff, pectoralis major, and biceps. Neurovascular exam and sensation were normal. DIFFERENTIAL DIAGNOSIS: 1. Traumatic hematoma 2. Lipoma 3. Abscess 4. Seroma TEST AND RESULTS: Left shoulder radiograph: - Heterotopic ossifications along the pectoralis tendon near humeral insertion. MRI left shoulder: - Sizeable fluid mass anterior to pectoralis major tendon measuring 6.1 x 3.9 cm with a communication tract to the humeral site of previous pectoralis tendon reattachment.FINAL WORKING DIAGNOSIS: Soft tissue abscess with proximal humeral osteomyelitis TREATMENT AND OUTCOMES: 1. Aspiration removed 60 cc of serosanguinous fluid. 2. Repeat MRI with contrast showed a decrease in abscess size to 5.2 x 1.7 cm and edema in the proximal humerus, suggesting chronic osteomyelitis. 3. Due to indolent presentation and prior surgery near axilla the etiology of infection was concerning for Propionibacterium acnes; patient was started on twice daily doxycycline. 4. Cleared to return to sport without restriction; pain and swelling improved with antibiotic and repeat aspiration. 5. Fluid cultures were negative at 2 weeks. 6. Plan for repeat MRI at the end of the season with potential irrigation and debridement if no significant improvement from weeks on oral antibiotic.