Chronic myelogenous leukemia. Development of blast crisis with both lymphoid and myeloid features

K. M. Skubitz, P. R. Craddock, D. J. Weisdorf, J. E. Niedel, T. W. LeBien, J. H. Kersey, R. D. Brunning, J. L. Parkin, P. J. Flynn and D. E. Hammerschmidt

A 50-year-old man had chronic myelogenous leukemia and entered a blast crisis that was both morphologically and histochemically lymphoid. The blasts contained terminal deoxyribonucleotidyl transferase and expressed lymphoblastic leukemia-associated antigen. He rapidly entered remission with vincristine sulfate and prednisone therapy. Nevertheless, his blasts displayed a marker generally considered unique to myeloid cells: they selectively bound the granulocyte chemotaxin N-formyl-Met-Leu-Phe. In addition, some cells contained granules resembling those of basophils or mast cells. Such mixed myeloid-lymphoid features in chronic myelogenous leukemia blast cells may reflect malignant transformation of a stem cell capable of both myeloid and lymphoid differentiation, or they may reflect the dedifferentiation as a feature of malignant change.