Tetrasomy 21 as a sole abnormality in erythroleukemia

A 13-year-old girl presented with swelling in the neck, fever, bleeding of the gums, and hepatosplenomegaly. Bone marrow morphology was suggestive of erythroleukemia (AML0M6). Chromosome analysis of the marrow revealed 48,XX, + 21, + 21 as the sole clonal abnormality.