Dual-color flow cytometric analysis of megakaryocytic DNA ploidy in the investigation of blastic phase chronic myelogenous leukemia with rearrangement of 3q26.

Abstract

A patient is described with chronic myelogenous leukemia in blastic crisis, in whom numerous circulating platelet fragments and megakaryocytic nuclei were present, with 50% blasts and 50% micromegakaryocytes in the marrow. The blasts expressed myeloid-associated antigens CD34, CD33, and CD13, whereas the micromegakaryocytes were positive for CD41, CD42b, and CD61. These findings suggested a myeloblastic transformation with a possible megakaryoblastic component. Cytogenetic analysis showed rearrangement of 3q26 in the form of t(2;3) (p13;q26), in addition to t(9;22) (q34;q11). Dual-color flow cytometric analysis of DNA content of CD42b-positive cells showed that the micromegakaryocytes were predominantly 2N, indicating a maturation block before nuclear endoreplication and polyploidization. These findings confirmed a combined myeloblastic and megakaryoblastic transformation. It is concluded that dual-color flow cytometric DNA analysis is a useful method for the investigation of abnormal megakaryocytopoiesis in hematologic malignancies.