Two Additional Acute Nonlymphocytic Leukemia Patients with a Sole Chromosome Abnormality of Trisomy 4

We report two cases of acute nonlymphocytic leukemia (ANLL) in which the circulating leukemic cells showed trisomy of chromosome 4 as the sole cytogenetic abnormality. Trisomy 4 is rarely found in hematopoietic neoplasia and until now the few reported patients had ANLL or myelodysplastic syndrome (MDS). In these two ANLL patients with trisomy 4 (FAB-M2 and M4), we were unable to obtain information on exposure to mutagenic/carcinogenic agents. Furthermore, both of them did not manifest underlying dysplastic changes in the bone marrow and also had cells with a normal karyotype. In addition the presence of cells with trisomy 4 without associated marrow dysplasia indicates that this karyotypic change may also occur in some ANLL patients without preexisting MDS.