CBFB and acute myelomonocytic leukemia M4: Acute myelomonocytic leukemia with eosinophilia, formerly known as FAB AML M4Eo, is a rare form of acute myeloid leukemia (AML) which is characterized by chromosome 16 abnormalities [(inv(16)(p13.1q22) or t(16;16)(p13.1;q22)/CBFB::MYH11] [11,24].