An Infant with Precursor Natural Killer (NK) Cell Leukemia Successfully Treated with an Unrelated Cord Blood Transplantation

Here we report a case with precursor natural killer (NK) cell leukemia successfully treated with an unrelated cord blood transplantation. A 7-month-old Japanese boy was diagnosed to have NK cell leukemia based on the existence of abnormal cells in the bone marrow with the phenotype of CD3(-) /CD4(+) /CD7(-) /CD8(-) /CD16(-) /CD33(+) /CD34(-) /CD56(+) /HLA-DR(+) /NKB1(+) / CD94(+). The leukemic cells showed few azurophilic granules in the cytoplasm and weak cytotoxic activity. Although he presented with a huge mass occupying the bilateral paranasal sinuses and hepatosplenomegaly, he achieved complete remission by the conventional chemotherapeutic regimen for acute myelogenous leukemia, followed by an unrelated cord blood transplantation. He has remained in complete remission for 14 months posttransplant. To our knowledge, this is the youngest reported case with precursor NK cell leukemia; cord blood transplantation may thus be the treatment of choice for this disease.