Unusual clinical presentation of malignant histiocytosis in a 70-year-old woman.

A 70-year-old woman was admitted for evaluation of hepatosplenomegaly, fever and elevated serum LDH levels. A biopsy specimen of the liver revealed histiocytic proliferation at the portal triad, and a mild degree of hepatitis. A bone marrow biopsy specimen showed proliferation of histiocytes with minimal immaturity and atypism, and haemophagocytosis by the proliferated histiocytes. Fever, hepatosplenomegaly and elevation of LDH levels all disappeared spontaneously, and presumptive diagnosis of benign reticulosis with haemophagocytosis was made. One year later, fever, hepatosplenomegaly and elevation of LDH levels redeveloped, and the liver and bone marrow biopsy specimen showed proliferation of unequivocally malignant histiocytes. The patient died as a result of disseminated intravascular coagulation with shock 20 d later. We concluded that, in this case, malignant histiocytosis first presented as benign haemophagocytic reticulosis and, 1 year later, there was a typical malignant presentation.