Trisomy 5 in two cases of acute monocytic leukemia with hyperdiploid clones.

Although numerical chromosomal aberrations are commonly seen in acute myeloid leukemia (AML), trisomy 5 (+ 5) is very rarely detected. We report two patients, both of whom suffered from acute monocytic leukemia, in which + 5 was found in hyperdiploid clones. A review of the English literature shows 17 additional cases of AML with + 5 in at least one of the abnormal clones, making a total of 19 such cases including ours. Trisomy 5 has been reported in all FAB subtypes of AML except acute promyelocytic leukemia. In the 19 cases identified in this report, + 5 was found in association with other numerical changes (four cases), structural changes (five cases) or both (eight cases). Trisomy 5 as a sole karyotypic abnormality was exceedingly rare (two cases). Its biologic and prognostic significance remains to be determined.