ⓘ Monoclonal B-cell lymphocytosis
Monoclonal B-cell lymphocytosis is an asymptomatic condition in which individuals have increased blood levels of particular subtypes of monoclonal lymphocytes. This increase must persist for at least 3 months. The lymphocyte subtypes are B-cells that share certain features with the abnormal clones of lymphocytes that circulate in chronic lymphocytic leukemia/small lymphocyte lymphoma or, less frequently, other types of B-cell malignancies. Some individuals with these circulating B-cells develop CLL/SLL or the lymphoma types indicated by their circulating monoclonal B-cells. Hence, MBL is a premalignant disorder
In 2017, the world health organization who reclassified MBL as a separate legal entity, in which individuals: 1) an excessive amount of circulating monoclonal b-cells, 2) absence of lymphadenopathy, organomegaly, or other tissue lesions caused by these cells, 3) no any other B cell lymphoproliferative disorders such as one of b-cell lymphomas, and 4) evidence that these cells have either CLL / SLL, atypical CLL / SLL, or non-CLL / SLL phenotype on the basis of these expressions cell specific protein marker. The fourth phenotype MBL, monoclonal B-cell lymphocytosis-marginal zone, i.e. MBL-MZ appears to be emerging in different forms of CLL / SLL MBL.
MBL consist of two groups: low-count MBL blood B-cells 90 can reach 75%. Age along with B-blood cells, major League baseball phenotype, and some genetic abnormalities in monoclonal b-lymphocytes are the most important factors when assessing the clinical manifestations of MBL and its necessity in management.