Treatment of calcinosis circumscripta with probenecid

A 23-year-old woman presented with an 11-year history of peripheral joint pains and stiffness slowly progressing to the development of gross calcinosis circumscripta. She had no definite evidence of systemic scleroderma. She was first treated for one year with frequent intravenous sodium EDTA, which increased urinary calcium and enhanced negative calcium balance but did not lessen her calcinosis. She was then treated with probenecid up to 2 g daily and her calcinosis lessened steadily over three years. Plasma levels of both phosphorus and urate fell during this time.