Pectoralis major muscle abscess in an immunocompromised adult: Case report and literature review

INTRODUCTION: Primary chest wall abscess is considered a rare disease. PRESENTATION OF CASE: A 60-year-old man presented with swelling of the pectoral muscle in the left side of his chest. Needle aspiration revealed pus. Computed tomography discovered fluid build-up anterior to the left pectoralis major muscle extending up to the left shoulder. There were multiple air pockets within the pectoralis major muscle and the surrounding fat stranding. Following antibiotic administration, we performed surgical debridement and irrigated the affected region. During surgery, the pectoralis major muscle was partially damaged; necrotic tissue was found only within the muscle. We diagnosed this condition as a pectoralis muscle abscess that most likely developed spontaneously from hematogenous spread. His postoperative course was uneventful, and there was no recurrence during a 3-month follow-up. DISCUSSION: Pyomyositis is an acute infection of the skeletal muscle. Although it is more commonly found in tropical climates, it is also diagnosed in temperate climates in patients who are immunocompromised. Pyomyositis can be divided into three stages. Stage 1, which is considered the invasive stage, presents with low-grade fever, pain, local myalgia, and local edema but no pus collection. Stage 2, which is the purulent stage, presents with fever, severe muscle pain and tenderness, moderate edema, and abscesses. Stage 3 is diagnosed when sepsis develops secondary to S. aureus bacteremia. CONCLUSION: In immunocompromised patients, the detection of pyomyositis at the early stage is challenging; however, most patients present at stage 2 or 3, which can increase the risk of complications.