An Unusual Case of Giant Polymicrobial Shoulder Abscess Developing Two Decades After an Insect Bite: The Role of Chronic Intermittent Swelling as a Predisposing Factor.

Shoulder abscesses, commonly resulting from bacterial infections, can occasionally present with atypical etiologies and delayed onset. We report a rare case of a massive polymicrobial shoulder abscess developing two decades after an insect bite, emphasizing its clinical presentation, diagnostic approach, and surgical management. A 65-year-old female presented with severe, progressively worsening right shoulder pain, a 20 cm swelling, and purulent discharge persisting for 15 days. Her medical history revealed hypertension, diabetes, and intermittent swelling in the insect-bitten region over the years, which likely predisposed the area to recurrent infections. No evidence of autoimmune disorders, corticosteroid use, or dental abscess was identified. Clinical examination revealed a purulent yellow discharge from the superolateral region of the right shoulder. Ultrasonography and contrast-enhanced MRI confirmed a localized subcutaneous abscess without muscle invasion. The surgical intervention included open irrigation and debridement, revealing dense, purulent, caseous, malodorous material with necrotic debris. Microbiological analysis identified anaerobic streptococci, anaerobic gram-negative bacilli, anaerobic non-spore-forming gram-positive rods,