Acute lymphoblastic leukemia terminating as histiocytic medullary reticulosis.

A young man with acute lymphoblastic leukemia was treated with vincristine sulfate, prednisone, and intrathecally injected methotrexate sodium for central nervous system involvement. A good remission was induced, but three months later he had hepatosplenomegaly, an enlarging mediastinal mass, and progressive anemia. Histiocytic medullary reticulosis was confirmed by a bone marrow biopsy specimen. The patient died of respiratory failure because of infiltration of the lungs by malignant histiocytes.