Heterogeneity of morphological, cytochemical, and cytogenetic features in the blastic phase of chronic granulocytic leukemia.

Possible predictive criteria of the refractoriness to therapy of the blastic phase of Ph-1-positive chronic granulocytic leukemia (CGL) have been sought. Eight cases in the blastic phase were studied. The blasts were noted to be of two types: some displayed a high nuclear:cytoplasmic ratio with deep blue cytoplasm, while others had a comparatively low nuclear:cytoplasmic ratio and bluish gray cytoplasm containing a few small granules. Electron microscopic studies showed a variety of features, including defective organelles and giant mitochondria. Cytochemical staining revealed the majority of blast cells to be peroxidase- and Sudan black-negative; granular PAS positivity was the rule. Serial cytogenetic studies demonstrated increasing aneuploidy. Bone marrow biopsy showed myelofibrotic changes in two cases. Two patients entered complete remission with prednisone and vincristine and with Ara-C and thioguanine, respectively. It is concluded that the blastic phase of CGL may manifest heterogeneity.