A novel variant three-way translocation of inversion 16 in a case of AML-M4eo following low dose methotrexate therapy

We report a case of acute myelomonocytic leukemia with eosinophilia (AML-M4 eo) in a 65-year-old man following low dose methotrexate treatment for pemp higus vulgaris. Cytogenetic studies at diagnosis revealed a complex karyoty pe including a reciprocal translocation between 11q14.2 and 16q22, an inver sion of chromosome 16(p13.1q22), and an apparently terminal deletion of 7q3 1. The presence of inv(16) was confirmed by reverse transcription-polymeras e chain reaction which demonstrated a Type A fusion transcript derived from the core binding factor(CBF) P and the smooth muscle myosin heavy chain (M YH11) genes. The patient was in complete hematologic and cytogenetic remiss ion 6 months following intensive chemotherapy. Because AML-M4eo with inv(16 ) has a favorable prognosis, molecular studies should be performed in case the identification of inv(16) by conventional cytogenetics is difficult due to a complex karyotype. (C) 2001 Elsevier Science Inc. All rights reserved .