[Aggressive NK-cell leukemia with sustained relapse-free survival after allogeneic peripheral blood stem cell transplantation].

A 46-year-old Japanese man was admitted to our hospital because of prolonged fever. Laboratory examination demonstrated leukopenia, thrombocytopenia, marked liver dysfunction, and elevation of serum ferritin. A bone marrow examination showed several hemophagocytic macrophages, and a diagnosis of hemophagocytic syndrome was made. He was treated using HLH-94 protocol, and his clinical symptoms and laboratory data were rapidly improved. After 5 weeks, fever and liver dysfunction reappeared. A repeat bone marrow examination demonstrated that 28.4% of marrow nucleated cells were atypical lymphocytes, which were positive for CD2, CD7, CD16, CD56, and HLA-DR. Clonality of these proliferating NK cells was confirmed by an analysis of EB virus terminal repeat sequence and cytogenetic analysis, and final diagnosis of aggressive NK-cell leukemia was made. After induction chemotherapy consisting of dexamethasone, etoposide, ifosfamide, and L-asparaginase, the patient achieved partial remission. He received allogeneic peripheral blood stem cell transplantation from his one locus mismatched son, and is alive with no evidence of disease 20 months after transplantation.