Monoclonal B-Cell Lymphocytosis, Chronic Lymphocytic Leukemia Type

**Semantic type:** Neoplastic Process

**Definition:** Monoclonal B-cell lymphocytosis characterized by the presence of more than 5 x 10^9/L abnormal B-lymphocytes in peripheral blood and presence of the characteristic immunophenotype of chronic lymphocytic leukemia. This type of monoclonal B-cell lymphocytosis evolves to chronic lymphocytic leukemia at a rate of 1-2% per year.

**Synonyms:** - High Count Monoclonal B-Cell Lymphocytosis