Acute leukemia occurring during chronic lymphocytic leukemia.

By PETER McPHEDiw r AND CLARK W. HEATH, JR. T HE CONCEPT OF “BLAST CRISIS” in chronic leukemia implies a single disease process advancing from chronic to acute phase. How often this happens in chronic lymphocytic leukemia, or whether it happens at all, is uncertain. Unlike chronic granulocytic leukemia, chronic lymphocytic leukemia does not often end in acute leukemia. While it is possible that occasional cases may have a true blast phase, the relative significance of such events can only be assessed by: (1) studying the cell types of acute leukemia occurring in chronic lymphocytic leukemia, and (2) measuring the frequency with which such cases occur. This report describes two instances of acute leukemia in patients with chronic lymphocytic leukemia, examines the incidence of such cases in a general population, and reviews the frequency and cytology of similar cases reported in the medical literature.