<b>Background:</b> Acute myeloid leukemia (AML) with <i>CBFB</i>::<i>MYH11</i> fusion and myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions (MLN-TK) are genetically defined and typically mutually exclusive entities. The gene discussed is CBFB; the disease is acute myeloid leukemia.