Trisomy 4: clinical picture, hematology, and survival. Presentation of two cases and review of the literature.

Two patients with acute nonlymphocytic leukemia (ANLL) and trisomy 4 as the only cytogenetic aberration are presented. Including the two, a total of 31 cases with this karyotype have been described till now. A review of the 31 cases shows that they fall into two distinct age groups, a younger group of 10 patients (5-34 years) and an older group of 21 patients (50-75 years). With four exceptions the diagnosis was ANLL in all cases, mostly FAB classes M2 and M4. At the time of diagnosis 18 had clinical signs of active infection. In 20 cases the peripheral leukocyte count was above 10 x 10(9)/L but not associated with presence/absence of infection. The median survival was 17 months from diagnosis. Independent prognostic factors were diagnosis (p = 0.01), peripheral leukocyte count (p = 0.03), and percentage of metaphases with trisomy 4 (p = 0.04). The two age groups as well as presence/absence of infection at the time of diagnosis were without significant prognostic consequences.