[1319] Cutaneous Marginal Zone Lymphomas with Plasmacytic Differentiation (CMZL-PD) Have Distinctive Features

JE Edinger, SH Swerdlow. University of Pittsburgh Sch. of Med., Pittsburgh, PA

Background: A recent study has suggested that many primary CMZL lymphomas are distinct from most other MALT lymphomas because of a lack of IgM expression based on molecular studies, CXCR3 negativity (except in the IgM+ cases) and a distinct T-cell environment (Blood,112:3355). Limited data exists concerning IHC defined heavy chain (HC) expression and correlation with other B and T-cell phenotypic & immunoarchitectural features.
Design: 27 CMZL-PD were stained for CD20, CD3, kappa, lambda, IgG, IgM, IgD, CXCR3, FOXP3, IgA, IgE, CD4, CD8, CD25, PD1, TIA-1, granzyme B, CD10, bcl-6, CD21, CD5, & cyclin D1 whenever sufficient material was available. The first 8 stains were available in all cases. The dominant HC in the plasma cells (PC) and CXCR3 expression in B-cells were assessed as well as the relative proportions of B-cells, T-cells and T-cell subsets. Available clinical data was reviewed.
Results: The CMZL from 13 males & 14 females (25-83 yrs old) were located on the head & neck (3), trunk (6) or extremities (16)(2 unknown). Only 1/27 patients died (cause unknown). 22 cases showed B-cells predominantly scattered & in aggregates vs. in sheets. The PC were IgG+ in 16 cases, IgM+ in 4 (1 patient with lung MALT), IgA+ in 1, biclonal with IgGλ & IgMκ PC in 1, IgG+ & IgE+ in 1 & uncertain in 4. The IgE stain also highlighted prominent mast cells in many cases. The B-cells were CXCR3- in 25 cases with the 2 CXCR3+ cases IgM+. BCL6+, CD10- germinal centers (GC) were present in 10 cases with CD10+ GC in 6. CD4:CD8 ratios were >1 in 14/15 cases and appeared >3 in 9. There were ≤5% FoxP3 Tregs in 22/25 cases & <10% in the rest. All cases evaluated (23) had scattered TIA1+, mostly granzyme B- cytotoxic cells (<5% in 19, 5-10% in 3, 10-20% in 1). PD1+ T-cells comprised <5% of total lymphocytes in 16/23 cases with ∼5-10% in 7.
Conclusions: CMZL-PD most typically show HC class switching in the PC (IgG>>IgA or IgE), often have previously undescribed prominent mast cells, and are usually very T-cell rich with predominantly CD4+ T-cells and only scattered Treg, non-activated cytotoxic cells, & follicular helper T-cells. While also appearing to be distinctive because at least many B-cells are CXCR3- especially in the IgM- cases, the possibility that many of the B-cells evaluated are non-neoplastic must be considered. Cases with IgM+ PC, sheets of B-cells, and CXCR3+ B-cells should raise the possibility of secondary skin involvement. It is also important to exclude the possibility of T-cell lymphomas with light chain restricted plasma cells.
Category: Hematopathology

Monday, March 22, 2010 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 180, Monday Morning


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