Tophaceous gout in a renal allograft recipient.

A 65-year-old female received a renal transplantation 3 years ago, and her maintenance immunosuppressive regimen included prednisolone 5 mg once daily (0.1 mg/kg/day), mycophenolate mofetil 1 g twice daily and cyclosporin 125 mg twice daily (5 mg/kg/day) with average trough serum levels of cyclosporine between 200 and 300 ng/mL since 3 months after renal transplantation. Her first episode of gouty arthritis developed more than 10 years ago; however, the disease activity remained quiescent, and there was no episode of gouty arthritis since 7 years before renal transplantation. It was not until 2 years ago, i.e. 1 year after transplantation, when the tophi first appeared on the left hand during an episode of gouty arthritis, which was followed by frequent attacks since then. On admission, physical examination disclosed multiple tophi on the left hand (Figure 1A) with exudation of white, chalky material from some tophi. Laboratory evaluation showed a higher level of serum uric acid, up to 7.7 mg/dL, but the level of urinary uric acid excretion was lower, at 175 mg/day (1 mmoL/day), and the creatinine clearance rate was 63 mL/min/1.73 m2 of body surface area. The radiograph of the left hand (Figure 1B) demonstrated soft-tissue swelling (arrowhead), para-articular erosions and overhanging margin (arrows) involving the left third metacarpophalangeal (MCP) joint. Polarized light microscopy demonstrated a myriad of extracellular urate crystals. She was then treated with prednisolone, low-dose colchicine and allopurinol, with a great improvement in the clinical course in the following months.

Fig. 1

Joint manifestations and radiograph characteristics of tophaceous gout in a 65-year-old woman after renal transplantation. Physical examination disclosed multiple tophi containing white, chalky material underneath the surface of the skin of the third metacarpophalangeal (MCP) joint of the left hand (A). The radiograph (B) demonstrated soft-tissue swelling (arrowhead), para-articular erosions and overhanging margin (arrows) involving the left third MCP joint.

Tophaceous gout is characterized by collections of solid urate in the connective tissues. The diagnosis of gout is most conclusive with the visualization of urate crystals in a sample of joint or bursal fluid and in the material obtained from a tophus or when it is demonstrated histologically in excised tissue. Bone erosions due to tophaceous gout may have delicate ‘overhanging’ edges and punctate as well as diffuse soft-tissue swelling with or without calcification. Organ transplant recipients treated with cyclosporine are at increased risk for the accelerated development of chronic tophaceous gout [1]. Cyclosporine might induce urate retention by either decreasing the glomerular filtration rate or impairing urate secretion through the mechanism of tubular damage [2]. Gouty arthritis has been reported in 7% to 24% of cyclosporine-treated patients [1,3]. Gout frequently occurs as a de novo event, although patients with a prior history of gout are at higher risk. De novo tophaceous gout generally appears about 17 to 24 months after transplantation. Thus, a detailed history of previous quiescent gout should be attained in patients with a new onset of tophi within 1 to 2 years after transplantation. As to the treatment, in addition to the prescription of a low-purine diet, medications for symptomatic relief and reduction of serum uric acid levels, judicious titration of cyclosporine doses according to renal function should also be considered in kidney transplant recipients with frequent gout attacks.