title: What does it mean I have a monoclonal B-cell lymphocytosis?: Recent insights and new challenges.
abstract: Monoclonal B-cell lymphocytosis (MBL) is defined as a laboratory abnormality where small (<5 x 10(9)/L) clonal B-cell populations are detected in the peripheral blood of otherwise healthy subjects. According to the immunophenotype, MBL is labeled as chronic lymphocytic leukemia (CLL)-like (75% of cases), atypical CLL, and CD5-negative. Concentration of clonal B cells differentiates low- (LC) and high-count (HC)-MBL (< or ≥ 0.5 x 10(9)/L, respectively). Thanks to technical improvements, we are able to identify CLL-like clonal B-cell populations at increased frequency with age, but we are still far from understanding its relationship with clinically overt CLL. LC-MBL, requiring high-throughput screening technique to be identified in population studies, seems to be a bird of a different feather and several hints suggest that LC-MBL is related to aging and/or chronic antigenic stimulation. Immunogenetic, cytogenetic and genetic data support the notion that HC-MBL, usually identified in the clinical setting, is a premalignant condition and, based on biological parameters, it is frequently difficult to differentiate it from early stage CLL. The rapid improvement and widespread availability of cutting-edge technology, in particular next-generation sequencing (NGS), raises hope that we are getting closer to unveiling the fundamental nature of MBL and CLL and how they are related to each other.
authors.affiliation: Department of Onco-Haematology and Division of Experimental Oncology, IRCCS San Raffaele Hospital and Università Vita-Salute San Raffaele, Milan, Italy. Electronic address: scarfo.lydia@hsr.it.
authors.forename: Lydia
authors.initials: L
authors.lastname: Scarfò
authors.affiliation: Department of Onco-Haematology and Division of Experimental Oncology, IRCCS San Raffaele Hospital and Università Vita-Salute San Raffaele, Milan, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Ghia
mesh_terms: D001402:B-Lymphocytes / Q000378:metabolism / Q000473:pathology*; D060833:Cellular Microenvironment; D060965:Clonal Evolution / Q000235:genetics; D020732:Cytogenetic Analysis; D003937:Diagnosis, Differential; D019468:Disease Management; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D016130:Immunophenotyping; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism / Q000628:therapy; D018655:Lymphocyte Count; D008218:Lymphocytosis / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism / Q000628:therapy
chemical_list: D007143:Immunoglobulin Heavy Chains
keywords: Chronic lymphocytic leukemia; Cytogenetic; Immunoglobulin genes; Monoclonal B-cell lymphocytosis; Next-generation sequencing