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IgG‐secreting lymphoplasmacytoid leukaemia: a B‐cell disorder with extensively mutated V H genes undergoing Ig isotype‐switching frequently associated with trisomy 12
Author(s) -
Garand Richard,
Sahota Surinder S.,
AvetLoiseau Hervé,
Talmant Pascaline,
Robillard Nelly,
Moreau Anne,
Gaillard Fanny,
Stevenson Freda K.,
Bataille Régis
Publication year - 2000
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1046/j.1365-2141.2000.01971.x
Subject(s) - cd5 , isotype , immunophenotyping , cd23 , biology , immunology , immunoglobulin class switching , cd19 , bone marrow , immunoglobulin d , waldenstrom macroglobulinemia , immunoglobulin gene , cd38 , cd20 , b cell , lymphoplasmacytic lymphoma , pathology , antibody , immunoglobulin e , monoclonal antibody , medicine , lymphoma , antigen , genetics , cd34 , stem cell
We investigated 16 patients with elevated serum monoclonal IgG and a leukaemic B‐cell lymphocytic disorder different from multiple myeloma. Their clinical history was that of a non‐aggressive disease with dominant splenomegaly and long survival. Whereas abnormal blood and bone marrow cells were predominantly small lymphocytes with a few lymphoplasmacytoid cells, histopathological features included a lymphoplasmacytic infiltrate in eight cases. Most frequently, abnormal blood cells displayed a CD19 + CD5 − CD23 +/– immunophenotype different from that of chronic lymphocytic leukaemia, except in two cases with a CD19 + CD5 + CD23 + phenotype. Interestingly, a coexistent serum monoclonal IgM and/or surface IgMG + with identical light chain was identified in 10 patients, whereas in the remaining six patients only IgG expression was determined. V H gene analysis was performed in eight patients to investigate the clonal origins of tumour cells. All cases utilized the V H 3 family, with evidence of extensive somatic mutations and intraclonal homogeneity in all cases. V H gene analysis indicated a clonal relationship between cells expressing IgM and IgG, with one case being biclonal. Cytogenetic evaluation showed a high incidence of trisomy 12 (60%) and 13q14 deletion (40%). In conclusion, we have described an unusual subset of low‐grade lymphoma with high‐serum IgG and frequent lymphoplasmacytoid features in which tumour cells derive from post‐follicular memory B cells undergoing isotype switching with some cases arrested at both the IgM and IgG stage and others as IgG‐positive cells only.