Natural killer cell acute leukemia with myeloid antigen expression: A previously undescribed form of acute leukemia

An acute leukemia of natural killer cell origin with myeloid antigen expression has not previously been described in the literature. Although lymphoproliferative disorders of large granular lymphocytes may be of natural killer cell origin and may have an aggressive clinical course, the morphology in the blood and bone marrow is that of large granular lymphocytes. An acute leukemia with blastic morphology is described, which was of natural killer cell origin by flow cytometric immunophenotyping (CD45+, CD2+, CD3, CD7+, CD5+, CD4, CD8, CD56+,CD57, CD16, CD13+, CD33+, CD34+, C-Kit+, HLA-DR, TdT) and histochemical staining. This was supported by the lack of T-cell gene rearrangement. The patient had an aggressive clinical course despite therapy for acute lymphoblastic leukemia. The authors recommend routine flow cytometric immunophenotyping of acute leukemia to identify other similar cases to better clinically define this entity.