Overhanging Edge Bone Erosion in Chronic Tophaceous Gout.

A 60-year-old man with a 30-year history of gout presented with a fever and polyarthralgia. A physical examination revealed deformities of the hands (Picture 1A, green arrows). Laboratory data showed that the C-reactive protein, rheumatoid factor, and anti-cyclic citrullinated peptide antibody levels were 21.3 mg/dL (reference range <0.15), 12 IU/mL (<15), and <0.6 U/mL (<4.5), respectively. Radiographs of the hands (Picture 1B, 2A, B) and right shoulder (Picture 2C) revealed bone erosion with overhanging edge (yellow arrows) and bone destruction (red arrows). Gallium-67 scintigraphy revealed a marked uptake in the affected joints (Picture 3A, B). Computed tomography of the shoulders revealed overhanging edge bone erosion (Picture 2D, E) and ectopic calcification in the muscle around the shoulder joints (Picture 3C). A synovial fluid examination of the right shoulder, right elbow, and both knee joints revealed uric acid crystals. Chronic tophaceous gout, an inflammatory polyarthritis due to chronic persistent gout, is often mistaken for rheumatoid arthritis and characterized by the differentiating radiographic feature of punched-out erosion with an “overhanging edge” (1). The radiographic finding of ectopic calcification (2) of the muscle soft tissue near the affected sites aids in diagnosing chronic tophaceous gout.

Picture 1.

Picture 2.

Picture 3.

The authors state that they have no Conflict of Interest (COI).