Sternoclavicular joint involvement in polyarticular gout: a crystal-proven case report

Abstract

Gout is a common crystal arthropathy that typically affects the lower extremities; involvement of the sternoclavicular joint (SCJ) is rare. We report a 60-year-old man with a two-year history of episodic polyarthritis who presented with left SCJ swelling of two months’ duration. Examination, radiography, and musculoskeletal ultrasonography (USG) demonstrated SCJ synovial effusion with an active power Doppler signal. USG-guided aspiration yielded approximately 2 mL of cloudy synovial fluid. Gram stain and bacterial cultures were negative, while polarized light microscopy revealed needle-shaped, negatively birefringent monosodium urate (MSU) crystals, confirming gout. The patient fulfilled the 2015 ACR/EULAR gout classification criteria. Treatment with allopurinol and concomitant colchicine flare prophylaxis was initiated. At 12-month follow-up, the patient remained flare-free, with resolution of SCJ swelling, serum uric acid reduced to 4.8 mg/dL, and normalization of inflammatory markers.