Discoid lupus erythematosus and tuberculosis simulating systemic lupus erythematosus.

A patient with chronic discoid lupus erythematosus was admitted with fever, arthralia, pleuropericarditis, and a history of leukopenia. He was initially believed to have systemic lupus erythematosus (SLE), but extensive evaluation showed negative immunologic studies and the presence of acid-fast organisms on pericardial biopsy specimens with cultures positive for Mycobacterium tuberculosis. Discoid lupus erythematosus patients with extracutaneous manifestations should be carefully studied for concurrent illness, especially when serologic evidence fo SLE is negative.