Trisomy 4 in a case of acute nonlymphocytic leukemia (M2)

Trisomy 4 in a Japanese patient with type M2 acute nonlymphocytic leukemia is reported. Karyotypic analysis was unsuccessful at diagnosis and complete remission lasted 4 years. The cytogenetic change was detected in the first and second relapses as the only chromosome abnormality. Unusual nuclear irregularities were found in many leukemic cells.