Acute myeloid leukemia with t(16;16) (p13;q22) showing a new CBFB-MYH11 fusion transcript associated with an atypical leukemic blasts morphology

Acute myeloid leukemia (AML) cases with inv(16)(p13q22) or t(16;16)(p13;q22) are characterized by multiple CBFB-MYH11 fusion transcripts, type A being the most frequent. Rare fusion variants are frequently correlated with an atypical cytomorphology, but their biologic and prognostic significance is unclear. We report a case of acute myeloid leukemia with a balanced t(16;16)(p13;q22) and additional monosomy 13 showing a new CBFB-MYH11 fusion transcript variant. The patient also showed an atypical morphology of bone marrow blasts, since about 15% of all blasts showed bilobed nuclei but there was no pathologic eosinophilia. The biologic and prognostic implications of this rare association are discussed.