Prolonged cytogenetic and hematologic remission of blastic transformation in chronic granulogytic leukemia

A patient with blastic transformation of Ph′ positive chronic granulocytic leukemia is presented in whom a long drug‐induced remission was achieved. Serial cytogenetic studies were performed through the course of the illness which demonstrated a major hypodiploid cell line associated with the blastic leukemia. Remission was accompanied by a return to the diploid chromosomal constitution which characterized the chronic phase of the disease. An unusual responsiveness to the effects of vincristine and prednisone was demonstrated by the case, which resulted in a survival of 28 months following the onset of blastic transformation. Eventual refractoriness to therapy was associated with a new cell line suggesting a pattern of clonal evolution. The Ph′ chromosome was present throughout the course of the disease.