Occurrence of a variant Philadelphia translocation, t(10;22), in de novo acute megakaryoblastic leukemia.

Acute megakaryoblastic leukemia (AMegL) in adults is a very rare subtype of acute myeloid leukemia (AML) and is characterized by a larger diversity of chromosomal abnormalities than the other subtypes, including 3q21q26 changes, aberrations of chromosomes 5 and 7, and the t(9;22)(q34;q11). We report the case of a 24-year-old patient with de novo AMegL and thrombocythemic cell count. Diagnosis was established with a bone marrow biopsy, and cytogenetics with G-banding revealed a t(10;22), which by FISH, was found to be a variant Philadelphia translocation involving chromosome 10q in all 20 metaphases analyzed. We believe that this is the first report of de novo AMegL with this chromosomal abnormality, and its possible correlation with morphology and thrombocytosis is discussed.