Blast Cell Crisis in Acute or Chronic Leukemia

PATIENTS with acute leukemia often have a modest elevation in the leukocyte count and many blast cells in the peripheral blood smear. This is true of both patients with acute lymphocytic leukemia and those with acute nonlymphocytic leukemia. Similarly, in the terminal stage of chronic granulocytic leukemia, patients commonly have an increase in white blood cells (WBCs), a percentage of which are blast forms in the peripheral blood. This situation does not occur in chronic lymphocytic leukemia. However, occasional patients with these diseases will have exceedingly high WBC counts, in excess of 100,000/ cu mm, and the blast cell level in the peripheral blood smear will likewise be in excess of 100,000/cu mm. Such a situation would then justifiably be called a "blast crisis." Patients with this finding deserve urgent medical therapy to forestall the development of leukocyte sludging in the vessels of the cerebral cortex. Subsequent diapedesis of leukemic