Trisomy 21 as the sole acquired karyotypic abnormality in an adult patient with CD7-positive acute myeloid leukemia.

We report a unique case of acute myeloid leukemia (AML) in which trisomy 21 was the sole acquired karyotypic abnormality. The blasts were positive for myeloperoxidase, and phenotypic analysis of peripheral blood cells by flow cytometry demonstrated positivity for CD7, CD13, CD33, and CD34. chromosomal analysis of peripheral blood and bone marrow cells showed trisomy 21; however, that of the buccal mucosal membrane revealed a normal karyotype. A diagnosis of CD7+AML (M2) with trisomy 21 was diagnosed and the patient achieved complete remission following treatment with Japan Adult Leukemia Study Group-AML97 protocol. This is the first reported case of CD7+AML with trisomy 21 as the sole cytogenetic abnormality.