lymphoplasmacytic lymphoma

Digital case

 HPC:279 : Lymphoplasmacytic lymphoma in the bone marrow.

Definition: Lymphoplasmacytic lymphoma (LPL) includes most cases of Waldenstrom macroglobulinemia and consists of a diffuse proliferation of small lymphocytes, plasmacytoid lymphocytes and plasma cells.

The typical histologic features of small lymphocytic lymphoma, mantle cell lymphoma and marginal zone lymphoma must be absent.

Immunophenotype

 Pan-B+
 CD5-
 CD10-
 cyIgM+

B-cell antigens are positive; whereas CD5 and, usually, CD23 test negative.

The cells express surface and cytoplasmic IgM and are IgD-.

CD10 is negative, whereas a proportion of cases have faint CD25 and CD11c expression.

The postulated normal counterpart is a B-lymphocyte differentiating into an IgM-secreting plasma cell.

The putative cell of origin is a peripheral B-lymphocyte transforming into plasma cell with mutated IgV genes and ongoing mutations.

Cytogenetics

 t(9;14)(p13;q32) (PAX5/IGH) (50% of cases) (9p13 and 14q32)

• The t(9;14)(p13;q32), fusing the IgH gene with the BSAP (B-cell specific activator protein), also called PAX5, has been found in 50% of the cases.
• This balanced translocation cannot be viewed as specific for this lymphoma, having been reported in rare marginal zone lymphomas and large cell lymphomas.

 other 14q32 translocations

• with 8q24 ( t(8;14)(q24;q32))
• 18q21 ( t(14;18)(q32;q21)

 trisomies of chromosomes 3 (+3; trisomy 3) and 12 (+12; trisomy 12) and an isochromosome 6p (i(6p))

References

 Cuneo A and Castoldi GL . Lymphoplasmacytic lymphoma. Atlas Genet Cytogenet Oncol Haematol. May 2000 . URL : http://AtlasGeneticsOncology.org/Anomalies/LPLID2074.html

 t(9;14)(p13;q32) denotes a subset of low-grade non-Hodgkin’s lymphoma with plasmacytoid differentiation. Offit K, Parsa NZ, Filippa D, Jhanwar SC, Chaganti RS. Blood. 1992 ; 80 (10) : 2594-2599. PMID 1384792

 A revised European-American classification of lymphoid neoplasms: a proposal from the International Lymphoma Study Group. Harris NL, Jaffe ES, Stein H, Banks PM, Chan JK, Cleary ML, Delsol G, De Wolf-Peeters C, Falini B, Gatter KC. Blood. 1994 ; 84 (5) : 1361-1392. PMID 8068936

 Genetics of small lymphocyte disorders. Panayiotidis P, Kotsi P. Seminars in hematology. 1999 ; 36 (2) : 171-177. PMID 10319386