[Acute myelomonocytic leukemia (M4) with CD19 antigen expression, eosinophilia and basophilia in bone marrow]

A 12-year old boy was admitted to Saitama Children's Medical Center because of fever and epistaxis. He had leukocytosis (WBC 40,800/microliters, blast 75%), anemia, thrombocytopenia and high levels of serum LDH, lysozyme, Vitamin B12, and plasma histamine. Bone marrow aspiration revealed hypercellular marrow with 31.2% blasts, 15.2% eosinophils, and 14.2% basophils. Blasts had Auer rods and were positive for peroxidase and negative for alpha-naphthyl butyrate esterase and PAS stainings. Ia, CD13 (My7), and CD19 (B4) antigens were expressed on his leukemic cells. Chromosomal study showed 46, XY, t(7;8) (q35;q22), del(9) (q13q22). Southern blot analysis using immunoglobulin constant region (C) probes revealed germline patterns of C mu, C kappa, C lambda, and breakpoint cluster region. A diagnosis of acute myelomonocytic leukemia (AMMoL, M4) was made. He attained a complete remission with daunorubicin and cytarabine, and 6 months later he received bone marrow transplantation from HLA-identical sister. This case had the common breakpoint 8q22 with ANLL with t(8;21) (q22;q22), and was unique AMMoL with proliferation of eosinophils and basophils in bone marrow.