Myeloproliferative diseases are a group of disorders associated with proliferation of one or more distinct cell lines. Patients can experience fatigue, weight loss, abdominal discomfort, easy bruising or bleeding, infections, as well as other symptoms. A specific diagnosis can be based on laboratory studies (. complete blood counts, leukocyte alkaline phosphatase score, polymerase chain reaction assay, serum uric acid level, red blood cell mass) and bone marrow biopsies, which would reflect a change in blood cell counts. Management of the myeloproliferative disease depends on the specific cause. Patients with chronic myelogenous leukemia can be treated with a number of chemotherapeutic agents. In comparison, treatment is targeted at supportive care for patients with polycythemia vera, essential thrombocythemia, and myelofibrosis. Chronic eosinophilic leukemia is characterized by increased eosinophils carrying genetic alterations in blood and bone marrow and is often associated with increased mast cells.