The Spectrum of B-cell and Plasma Cell Proliferations in Nodal T Follicular Helper Cell Lymphomas.

in The American journal of surgical pathology by Roman Segura-Rivera, Nicholas Joseph Dcunha, Yiannis Petros Dimopoulos, Aniruddha Mundhada, Tania P Sainz, Claudia Kettlun, Vishal Sahu, Iman Sarami, Roberto N Miranda, Pei Lin, Leonard Jeffrey Medeiros, Francisco Vega

TLDR

  • The study reviewed 414 cases of nTfh lymphoma and found 78 cases with B-cell or plasma cell proliferations, which were associated with neoplastic Tfh clones.
  • Most of these proliferations had little impact on the clinical course of patients with nTfh lymphoma, but some B-cell expansions exhibited aggressive morphologic features and may represent an independent B-cell lymphoma.

Abstract

B-cell and plasma cell proliferations are frequently observed in nodal T follicular helper (nTfh) cell lymphomas and can present a diagnostic challenge. These proliferations can be monotypic or monoclonal and morphologically resemble lymphoma or plasmacytoma, but their clinical behavior is poorly defined. In this study, we reviewed 414 cases of nTfh lymphoma seen over the past decade at our institution. We identified 78 (19%) cases that exhibited B-cell or plasma cell proliferation detected by morphology, flow cytometry, immunohistochemistry, and/or molecular techniques. The B-cell/plasma cell proliferations occurred before (22%), concurrently with (50%), or after (28%) the diagnosis of nTfh lymphoma. We divided them into 3 categories: (1) focal or scattered B-immunoblastic proliferations recognized morphologically without a monotypic/monoclonal B-cell population (17%), (2) monotypic/monoclonal B-cell/plasma cells identified solely by flow cytometry or molecular clonality studies without morphologic confirmation (11%), and (3) unequivocal B-cell/plasma cell expansions recognized by morphologic assessment (72%). We further subdivided group 3 into proliferations associated with and possibly dependent on neoplastic Tfh cells versus those proliferations occurring in the absence of neoplastic Tfh cells and likely bona fide lymphomas. Follow-up biopsy specimens showed persistence of B-cell/plasma cell proliferations in various patient subcategories, with transformation to higher-grade B-cell proliferation or persistence without Tfh cells in some cases. In conclusion, our data support the notion that most B-cell and plasma cell proliferations associated with neoplastic Tfh clones have little impact on the clinical course of patients with nTfh lymphoma and likely do not constitute an independent B-cell lymphoma, especially those of small B cells of plasma cells. However, B-cell expansions exhibiting aggressive morphologic features may represent an independent B-cell lymphoma.

Overview

  • The study aimed to investigate B-cell and plasma cell proliferations in nodal T follicular helper (nTfh) cell lymphomas, which can pose a diagnostic challenge.
  • The researchers reviewed 414 cases of nTfh lymphoma over a decade and identified 78 cases with B-cell or plasma cell proliferations.
  • The study aimed to investigate the clinical behavior and histological characteristics of these proliferations, as well as their association with neoplastic Tfh cells.

Comparative Analysis & Findings

  • The study divided the B-cell and plasma cell proliferations into three categories: focal or scattered immunoblastic proliferations, monotypic/monoclonal B-cell/plasma cells identified by flow cytometry or molecular clonality studies, and unequivocal B-cell/plasma cell expansions recognized by morphologic assessment.
  • The researchers found that most B-cell and plasma cell proliferations associated with neoplastic Tfh clones had little impact on the clinical course of patients with nTfh lymphoma.
  • However, B-cell expansions exhibiting aggressive morphologic features may represent an independent B-cell lymphoma.

Implications and Future Directions

  • The study highlights the importance of further investigating the clinical behavior and histological characteristics of B-cell and plasma cell proliferations associated with nTfh lymphoma.
  • Future studies should aim to better define the clinicopathological features of these proliferations and their relationship with neoplastic Tfh cells.
  • Additionally, the study suggests that B-cell proliferations exhibiting aggressive morphologic features may require distinct therapeutic approaches.
Read Full Article