AML M1 and M2 with eosinophilia and AML M4Eo: diagnostic and clinical aspects.

AML with eosinophilia belongs to the morphologic cytogenetic entity M1/M2 t(8;21) with the involvement of the genes AML1/ETO. These eosinophils differ only slightly from normal eosinophils with one rare exception i.e. Auer rods in eosinophils which has only been found on peroxidase staining: This subtype belongs to the good prognosis group of AML. AML with inv(16) (mostly M4Eo) per se is a morphologic-cytogenetic entity with inv(16),--rarely t(16;16), and the genes MYL 11/CBF beta involved. The eosinophils show special abnormalities. AML with inv(16) also belongs to the good prognosis group of AML.