A type of disease in which the bone marrow makes too many red blood cells, platelets, or certain white blood cells. Chronic myeloproliferative neoplasms usually get worse over time as the number of extra cells build up in the blood and/or bone marrow. This may cause bleeding problems, anemia, infection, fatigue, or other signs and symptoms. Certain chronic myeloproliferative neoplasms may become acute myeloid leukemia (AML). Chronic myeloproliferative neoplasms include chronic myelogenous leukemia (CML), polycythemia vera, primary myelofibrosis, essential thrombocythemia, chronic neutrophilic leukemia, and chronic eosinophilic leukemia. Also called myeloproliferative neoplasm.