[A female patient with near-tetraploid acute myeloid M4 leukemia]

Acute myeloid leukemias (AML) are a heterogeneous group of diseases, several types of them are well characterized by typical morphologic, immunologic and cytogenetic features of their leukemic blasts in the MIC classification. We have recently described 2 patients with a new AML type--poorly differentiated near-tetraploid AML L0. The occurrence of very large blasts in a heterogeneous blast population seemed to be a morphological sign of this new type of AML.

The same morphologic characteristics were observed by us when we studied blasts of another 80-year-old patient with a near-tetraploid karyotype. However, 34% of blasts were positive for myeloperoxidase and they exhibited in 24-33% surface myelomonocytic markers CD11b, CD13, CD15 and CD14. The illness was classified as acute myelomonoblastic leukemia M4 without significant dysplastic changes in erythroid and megakaryocytic lineages. The growth of granulocyte-macrophage bone marrow progenitors CFU-GM was low. The patient refused cytotoxic chemotherapy and expired 3 months later on supportive treatment.

The finding of very large blasts is a typical sign in cases of near-tetraploid AML. Precise classification of leukemia type is essential for successful therapy.