Systemic lupus erythematosus presenting with red lunulae.

Red lunulae have been observed in association with a large spectrum of cutaneous and systemic diseases. We describe a 13-year-old girl with painful red lunulae of the fingernails who subsequently developed systemic lupus erythematosus. The appearance of Beau's lines suggested inflammation of the nail matrix. Oral prednisone produced significant improvement in the nail changes. To our knowledge, red lunulae have not been previously recognized as the presenting sign of systemic lupus erythematosus.