A case of hemophagocytic lymphohistiocytosis with prolonged remission after syngeneic bone marrow transplantation.

We report a 7-year-old girl with hemophagocytic lymphohistiocytosis who received a syngeneic bone marrow transplant from her twin sister. She presented with high fever and cough. Laboratory findings revealed pancytopenia, elevation of liver enzymes, and hyperferritinemia. Bone marrow examination revealed histiocytic hemophagocytes and lymphoblastoid cells. Southern blot analysis of the bone marrow cells revealed a monoclonal proliferation of EBV-infected lymphocytes. Although she underwent combined chemotherapy according to the HLH-94 protocol, she developed severe pancytopenia. Following myeloablative conditioning with busulfan (16 mg/kg), cyclophosphamide (120 mg/kg), and etoposide (1.5 g/m2), she was transplanted with 6.6 x 10(8)/kg mononuclear cells from the twin sister. She remains in complete remission 23 months after transplantation.