Leukemia in which the involved cell is well differentiated, usually b-lymphocytes, but immunologically incompetent; types distinguished include chronic granulocytic, chronic lymphocytic, chronic myelomonocytic, eosinophilic and hairy cell leukemia.

Chronic leukemia is an increase of abnormal white blood cells. It differs from acute leukemia, and is categorized as myelogenous, lymphocytic or myeloproliferative. Chronic leukemia may refer to: Chronic myelogenous leukemia Chronic lymphocytic leukemia, including Hairy cell leukemia Myeloproliferative neoplasms including polycythemia vera, essential thrombocythemia, primary myelofibrosis, chronic neutrophilic leukemia , and chronic eosinophilic leukemia..