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Promyelocytes are larger, 15 - 25 microns in size and are granulocyte precursors capable of cell division, developing from myeloblast and maturing into myelocytes. Their cytoplasm is basophilic and contains abundant primary red/purple azurophilic granules.They have a pale area near nucleus called the Golgi zone ,site for producing granules. Their chromatin pattern is diffuse showing some condensation and few visible nucleoli. Clinical significance: Early recognition of abnormal promyelocytes in the peripheral blood smear and bone marrow is essential for diagnosis of APML in proper clinical context and characteristic molecular abnormality t (15;17) , without regard to blast count.