Acute megakaryocytic leukemia with the t(1;22)(p13;q13).

Acute megakaryocytic leukemia (AMKL) was defined as a new subtype of acute nonlymphocytic leukemia (ANLL) by the French-American-British (FAB) Cooperative Group in 1985. The first consistent chromosomal anomaly described in this subset of ANLL was the translocation t(1;22)(p13;q13) which appears to be restricted to this FAB-subtype (FAB-M7) of AML. To our knowledge, 18 AMKL cases with the t(1;22) have been reported until now in the literature. In all instances, the patients were very young children with only one beyond the infant age (12 months) at the time of diagnosis. Based on the results of two reports in which the frequency of this translocation was assessed, the t(1;22) may be estimated to occur in about 30% of pediatric patients with FAB-ANLL subtype M7. In infants with this subset of ANLL, the t(1;22) seems to be present in the majority (> 65%) of cases. The detection of this nonrandom chromosomal abnormality may therefore provide an additional diagnostic marker in children with AMKL. Herein we review and discuss the clinical and cytogenetic findings in patients with AMKL and the t(1;22).