Clinical images: Divergent patterns of joint remodeling following effective urate‐lowering therapy in tophaceous gout

Abstract

The patient, a 35-year-old man, presented with severe tophaceous gout and hyperuricemia (10.2 mg/dl), despite receiving combination treatment with allopurinol (300 mg daily) and benzbromarone (100 mg daily). He had a history of renal transplantation and was treated with cyclosporine; his serum creatinine level was 2.07 mg/dl. During a prolonged hospital admission in 2007 for treatment of an infected tophus affecting the calf, monthly administration of rasburicase (1) was initiated, leading to normalization of the serum urate levels (3.8–6.0 mg/dl) and a gradual reduction in tophus size. Baseline radiography showed large gouty erosions, particularly affecting the left middle finger proximal interphalangeal (PIP) joint and the right first metatarsophalangeal (MTP) joint (arrows in left panels of A and B). After 2 years of treatment with rasburicase, repeat radiography in 2009 showed some regression in the soft tissue masses and divergent patterns of joint remodeling at different sites, with collapse and telescoping of the left middle finger PIP joint, and new bone formation with ankylosis at the right first MTP joint (arrows in right panels of A and B). Osteoblast-mediated bone resorption and enhanced osteoclastogenesis have previously been implicated in the pathogenesis of bone erosion in chronic tophaceous gout (2,3). These images suggest that resorption of tophi may alter these cellular processes in contrasting ways, leading to different patterns of bone remodeling.