Malignant histiocytosis as a fatal complication of systemic lupus erythematosus.

We present the case of a 26-year-old Caucasian woman with systemic lupus erythematosus (SLE) of 9 years duration, mainly involving the kidney. Her clinical course was complicated in the last year by several infectious and noninfectious events, and after pancytopenia, fever, and extremely high levels of lactate dehydrogenase developed, the woman died. Light and electron microscopy of bone marrow, together with immunophenotyping, disclosed malignant histiocytosis, a complication of SLE that has not been reported.