Lymphoma-like monoclonal B cell lymphocytosis in a patient population: biology, natural evolution, and differences from CLL-like clones

Sam Vander Meeren, Bert Heyrman, Wim Renmans, Marleen Bakkus, Brigitte Maes, Hendrik De Raeve, Rik Schots, Kristin Jochmans

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High-count monoclonal B cell lymphocytosis (MBL) with a chronic lymphocytic leukemia (CLL) phenotype is a well-known entity, featuring 1–4% annual risk of progression towards CLL requiring treatment. Lymphoma-like MBL (L-MBL), on the other hand, remains poorly defined and data regarding outcome are lacking. We retrospectively evaluated 33 L-MBL cases within our hospital population and compared them to 95 subjects with CLL-like MBL (C-MBL). Diagnoses of L-MBL were based on asymptomatic B cell clones with Matutes score < 3, B cells < 5.0 × 10 3/μl, and negative computerized tomography scans. We found that median B cell counts were considerably lower compared to C-MBL (0.6 vs 2.3 × 10 3/μl) and remained stable over time. Based on immunophenotyping and immunogenetic profiling, most L-MBL clones did not correspond to known lymphoma entities. A strikingly high occurrence of paraproteinemia (48%), hypogammaglobulinemia (45%), and biclonality (21%) was seen; these incidences being significantly higher than in C-MBL (17, 21, and 5%, respectively). Unrelated monoclonal gammopathy of undetermined significance was a frequent feature, as the light chain type of 5/12 paraproteins detected was different from the clonal surface immunoglobulin. After 46-month median follow-up, 2/24 patients (8%) had progressed towards indolent lymphoma requiring no treatment. In contrast, 41% of C-MBL cases evolved to CLL and 17% required treatment. We conclude that clinical L-MBL is characterized by pronounced immune dysregulation and very slow or absent progression, clearly separating it from its CLL-like counterpart.

Original languageEnglish
Pages (from-to)1219-1227
Number of pages9
JournalAnnals of Hematology
Issue number7
Publication statusPublished - Jul 2018


  • Chronic lymphocytic leukemia
  • Immunophenotyping
  • MGUS
  • Monoclonal B cell lymphocytosis
  • Non-Hodgkin’s lymphoma
  • Receptors, IgE/analysis
  • Prognosis
  • Follow-Up Studies
  • Paraproteins/analysis
  • Clone Cells/pathology
  • Humans
  • Middle Aged
  • Male
  • Lymphoma, B-Cell/pathology
  • Preleukemia/pathology
  • CD5 Antigens/analysis
  • Monoclonal Gammopathy of Undetermined Significance/complications
  • Lymphocytosis/classification
  • Aged, 80 and over
  • Female
  • Retrospective Studies
  • Paraproteinemias/pathology
  • Diagnosis, Differential
  • Leukemia, Lymphocytic, Chronic, B-Cell/pathology
  • Agammaglobulinemia/pathology
  • Disease Progression
  • B-Lymphocytes/pathology
  • Gene Rearrangement, B-Lymphocyte, Heavy Chain
  • Aged


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