Hospital population screening reveals overrepresentation of CD5− monoclonal B-cell lymphocytosis and monoclonal gammopathy of undetermined significance of IgM type

Abstract

Monoclonal B-cell lymphocytosis (MBL) and monoclonal gammopathy of undetermined significance (MGUS) result from clonal expansions of mature B or plasma cells. Here, we set out to determine the immunophenotypic/monoclonal immunoglobulin (M protein) features and co-prevalence of MBL and MGUS in a hospital-based cohort of 1909 non-hematooncological patients. Of the evaluable cases, 3.8 % showed evidence for MBL by immunophenotyping, while 9.8 % were screened positive for M protein by immunofixation. With six concomitant cases (0.4 %), MBL and MGUS were not statistically associated. At least in two of these coincident cases, MBL and MGUS were of different clonal origin since both clones had divergent light chain restriction. CD5(-) MBL (57.1 %) and IgM+ MGUS (24.7 %) were strikingly overrepresented compared to population-based screenings and did not progress to overt lymphoma or myeloma during the observation period (mean follow-up of 117 weeks or 110 weeks, respectively). Prevalence and phenotypes suggest that a substantial proportion of incidental MBL and MGUS in hospitalized patients may be attributed to transiently expanded B-cell clones in the context of disease-related immune stimulation rather than reflecting veritable precursors of clonal B-cell malignancies.

Monoclonal gammopathies regardless of subtypes are associated with poor prognosis of diffuse large B-cell lymphoma

“…Therefore, they concluded that rather than polyclonal gammopathies which are regarded as a reaction of the anti-tumor response, MG may be attributed to disease-related immune stimulation. [ 19 ] Recent studies have introduced ratios of different kinds of peripheral blood cells to be used to predict prognosis of lymphoma. Watanabe et al revealed that LMR can reflect host systemic immunity and estimate clinical effects of R-CHOP treatments for DLBCL patients.…”

Immunophenotypic profile and clinical outcome of monoclonal B‐cell lymphocytosis in kidney transplantation

“…However, if we exclude that the stochastic association between MBL and MGUS was determined only by a higher rate of flow cytometry in patients affected by MGUS, the exact etiology of concomitant MBL and MGUS remains unknown. Recently, to confirm the hypothesis of the frequent association of MBL and MGUS (especially IgM), Voigtlaender et al found a nonstatistically significant coprevalence of 0.4% among a cohort of 1909 onco‐hematological patients; interestingly, all cases showed a non‐CLL phenotype. In another study, Xochelli et al reported the concomitant presence of a paraprotein in 33% of 102 patients with MBL, mostly of the non‐CLL subtype.…”

Monoclonal B-cell Lymphocytosis Exacerbated by Prednisolone Therapy for Dermatomyositis

“…An epidemiological study of 1909 non-hematooncological patients reported that although there were six cases with concomitant MBL and IgM-monoclonal gammopathy with undetermined significance (MGUS), there was no significant association between MBL and MGUS. In at least two of these coincident cases, MBL and MGUS were of different clonal origins, since both clones had divergent light chain restriction (11). There have been two case reports of concomitant MBL and MGUS (12,13), including one wherein both clones had divergent light chain restriction (12).…”