The biopsy specimen revealed amorphous pink to gray material in the dermis, surrounded by lymphocytes and multinucleated foreign body–type giant cells, with no evidence of vasculitis or panniculitis. A von Kossa stain was negative for calcium. These microscopic findings were consistent with a diagnosis of a gouty tophus. Laboratory data revealed normal levels of serum calcium and phosphorus and an elevated level of uric acid (12.2 mg/dL [to convert to micromoles per liter, multiply by 59.485]; reference range, 2.6-7.5 mg/dL).