del(6)(p23) in two cases of de novo AML--a new recurrent primary chromosome abnormality.

Objective: Previously, deletion 6p23 was generally reported in therapy-related secondary acute myeloid leukemia (AML) as part of complex karyotypes. In this report, we present two young adult patients with de novo AML-M2 and a terminal deletion 6p23 as a sole primary abnormality, confirmed by chromosome 6 specific subtelomeric probes.

Methods: Two female patients 35 and 20 yr of age presented with anemia, but no bleeding, infections, lymphadenopathy or organomegaly. Morphological, immunophenotyping, chromosome and fluorescent in situ hybridization (FISH) analysis was performed on bone marrow aspirate cells.

Results: A diagnosis of AML-M2 was confirmed in both patients by morphological and immunophenotyping studies. Chromosome analysis in case no. 1 showed deletion 6p23 in 20% of metaphases whereas in case no. 2 the deletion 6p23 was present in 100% metaphases. FISH analysis confirmed the deletion as terminal in both cases. The DEK oncogene at 6p23 in both cases was found not to be deleted.

Conclusion: To our knowledge, deletion 6p23 as a sole primary abnormality was reported in only one case. The common morphological, immunophenotypic, and cytogenetic features in our two patients strongly support a separate new entity of de novo AML with deletion 6p23.