TY - JOUR
T1 - Lymphoplasmacytic lymphoma with IgG or IgA paraprotein
T2 - a study of 29 cases including cases that can mimic plasma cell neoplasms
AU - Qiu, Lianqun
AU - Nwogbo, Okechukwu V.
AU - Medeiros, L. Jeffrey
AU - Thakral, Beenu
AU - Li, Shaoying
AU - Xu, Jie
AU - You, M. James
AU - Wang, Wei
AU - Quesada, Andres E.
AU - Ramos, Carlos Bueso
AU - McDonnell, Timothy J.
AU - Thomas, Sheeba K.
AU - Lin, Pei
N1 - Publisher Copyright:
© 2022 Elsevier Inc.
PY - 2022/12
Y1 - 2022/12
N2 - Lymphoplasmacytic lymphoma (LPL) with IgG or IgA paraprotein is rare and a subset of cases can mimic a plasma cell neoplasm (PCN). We studied 29 such cases to explore their clinicopathological features and the best diagnostic approaches with a focus on bone marrow findings. The cohort included 18 men and 11 women with a median age of 68 years. The median M protein was 3.1 g/dL, IgG in 19 patients (66%), IgA in 9 (31%), and dual IgG/IgA in 1 (3%). All patients had bone marrow involvement with CD138+ plasma cells (PCs) ranging from 1 to 35% (median, 10%). Two patients also had amyloidosis. Immunoglobulin light chain concordant monotypic PCs and monotypic B cells were identified in 96% of cases assessed by flow cytometry. Notably, the neoplastic PCs were consistently positive for CD45 (dim, 100%), CD19 (96%), CD81 (89%), CD27 (83%), rarely and only weakly or partially express CD56 (16%), whereas CD117 was consistently negative. Eleven cases analyzed by fluorescence in situ hybridization were negative for CCND1::IGH and myeloma-related aberrations. MYD88 mutation was detected in 17 of 24 cases (71%), and CXCR4 mutation was identified in 6 of 19 cases (32%), of which 4 had concurrent MYD88 mutation. In conclusion, the results highlight a potential diagnostic pitfall of LPL associated with marked plasmacytic differentiation and an IgG or IgA paraprotein that can resemble a PCN. Useful features in favor of LPL against PCN include the characteristic immunophenotypic profile of the PCs in LPL, absence of CCND1::IGH, and the presence of MYD88 and/or CXCR4 mutations.
AB - Lymphoplasmacytic lymphoma (LPL) with IgG or IgA paraprotein is rare and a subset of cases can mimic a plasma cell neoplasm (PCN). We studied 29 such cases to explore their clinicopathological features and the best diagnostic approaches with a focus on bone marrow findings. The cohort included 18 men and 11 women with a median age of 68 years. The median M protein was 3.1 g/dL, IgG in 19 patients (66%), IgA in 9 (31%), and dual IgG/IgA in 1 (3%). All patients had bone marrow involvement with CD138+ plasma cells (PCs) ranging from 1 to 35% (median, 10%). Two patients also had amyloidosis. Immunoglobulin light chain concordant monotypic PCs and monotypic B cells were identified in 96% of cases assessed by flow cytometry. Notably, the neoplastic PCs were consistently positive for CD45 (dim, 100%), CD19 (96%), CD81 (89%), CD27 (83%), rarely and only weakly or partially express CD56 (16%), whereas CD117 was consistently negative. Eleven cases analyzed by fluorescence in situ hybridization were negative for CCND1::IGH and myeloma-related aberrations. MYD88 mutation was detected in 17 of 24 cases (71%), and CXCR4 mutation was identified in 6 of 19 cases (32%), of which 4 had concurrent MYD88 mutation. In conclusion, the results highlight a potential diagnostic pitfall of LPL associated with marked plasmacytic differentiation and an IgG or IgA paraprotein that can resemble a PCN. Useful features in favor of LPL against PCN include the characteristic immunophenotypic profile of the PCs in LPL, absence of CCND1::IGH, and the presence of MYD88 and/or CXCR4 mutations.
KW - Diagnostic pitfall
KW - IgG or IgA paraprotein
KW - Immunophenotype
KW - Lymphoplasmacytic lymphoma
KW - Non-IgM paraprotein
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U2 - 10.1016/j.humpath.2022.10.005
DO - 10.1016/j.humpath.2022.10.005
M3 - Article
C2 - 36244464
AN - SCOPUS:85142121355
SN - 0046-8177
VL - 130
SP - 47
EP - 57
JO - Human Pathology
JF - Human Pathology
ER -