<prompt> Which of the following is not compatible with a diagnosis of chronic myelomonocytic leukemia ?Absence of Philadelphia chromosomeMore than 20 blasts in blood or bone marrowBoth a,bNone  <response>: Ans. is b i.e., More than 20 of blasts in blood or bone marrowChronic myelomonocytic leukemia CMML o The term myelomonocytic leukemia indicates that all cells of the myeloid lineage are involved myelo-, but emphasizes the prominence of monocytoid features -mono-.o The hallmarks of CMML are -i Peripheral monocytosis 1000 1 1 x 109 Lii 20 of bone marrow blastsiii Peripheral blood blasts 5iv Presence of bone marrow dysplasiao CMML is also known as philadelphia chromosome negative leukemia.o CMML shares clinical and biological features with both myelodysplastic syndrome MDS and chronic myeloproliferative disorders CMPDs, and may take on predominantly myelodysplastic MD - CMML or myeloproliferative MP - CMML characteristics.WHO diagnostic criteria for CMMLMajor criteria1. Persistent peripheral blood monocytosis 100 12. Absence of philadelphia chromosome or BCR Abl fusion gene.3. 20 myeloblasts tnonoblasts promonocytes in peripheral blood or bone marrow4. Dysplastic changes in one or more myeloid lineages.Minor criteria1. Acquired clonal cytogenetic abnormality in bone marrow cells.2. Persistent monocytosis 3 months, after exclusion of all other causes of monocytosis.o For the diagnosis of CMML all 4 major criteria must be present. In the absence of myelodysplasia, or when only minimal myelodysplasia is present, the diagnosis of CMML can be made when the first 3 criteria and at least one of the minor criteria are fulfilled.o CMML has been split into:- i CMML -1 10 bone marrow blastsCMML - 2 11-20 bone marrow blastsWHO criteria for the classification of CMMLCMML -1Bone marrow blasts 10Peripheral blood blasts 5CMML-2Bone marrow blasts 10-19Peripheral blood blasts 5-19OR : Presence of Auer rods when blasts in peripheral blood and bone marrow 20CMML -1 or CMML -2 with eosinophiliaAbove criteria for CMML - 1 or CMML - 2 ANDPeripheral blood absolute eosinophil count 1500 1 