This white lesion on the thumb of a 70-year-old man is surrounded by erythema. Analysis of fluid extracted after the lesion was lanced revealed negatively birefringent urate crystals, which confirmed a diagnosis of gout. Results of blood tests showed a serum uric acid level of 8.5 mg/dL (normal, 3.5 to 7.2 mg/dL). Monoarthritis is the classic presentation of gout (70%); polyarthritis is seen occasionally; nonarticulation sites, as seen in this case, are involved only rarely.
Photo courtesy of Doug Davenport and Samuel G. Poser, MD
