Erythrocytosis and marked leukocytosis in overlapping myeloproliferative diseases.

We describe two patients who had similar features of erythrocytosis and marked leukocytosis but who were subsequently classified as having chronic myelogenous leukemia and polycythemia vera, respectively, using leukocyte alkaline phosphatase scores and cytogenetic studies to detect the Philadelphia chromosome. The patient diagnosed as having polycythemia vera had a leukocyte count of 164,000/cu mm, which remained at similar levels when the patient was not in remission. We believe this is the first well documented case of PV with a leukocyte count above 150,000/cu mm.