Four months after the diagnosis of refractory anemia, a 60-year-old pa
tient developed acute leukemia with blast cells that were poorly diffe
rentiated by morphology and clearly myeloid by immunophenotyping. Cyto
genetic analysis performed at leukemization showed trisomy 13. An extr
a copy of chromosome 13 has already been reported in a few cases of ac
ute leukemia and myelodysplastic syndrome.