[1486] A Panel of Follicular Helper T-Cell (TFH) Immunophenotypic Markers Identifies and Differentiates TFH-Derived Neoplasms from Other T-Cell Neoplasms

Olga Pozdnyakova, Ali Shahsafaei, Gordon Freeman, David Dorfman. Brigham and Women's Hospital, Boston, MA; Dana Farber Cancer Institute, Boston, MA

Background: Recent studies have shown that T-cell derived neoplasms can be subdivided into TFH-derived and non-TFH-derived tumors based on the immunophenotypic profile. A panel of TFH immunophenotypic markers, including CD200, ICOS, and PD-1, is useful for the identification of TFH-derived neoplasms.
Design: We employed a panel of TFH immunophenotypic markers that included CD200, ICOS, and a new highly sensitive mouse monoclonal antibody for PD-1 (EH33), for characterization of TFH-derived neoplasms and differentiation from other T-cell neoplasms.
Results: Angioimmunoblastic T-cell lymphoma (AITCL) was immunoreactive for all TFH markers studied in the vast majority of cases, with diffuse (21 cases) or focal (11 cases) staining for PD-1. Cases of primary cutaneous CD4+ small/medium T-cell lymphoma (PCSMTCL) were also immunoreactive for all TFH markers studied. However, mycosis fungoides (MF) was typically immunoreactive for PD-1 (15/17 cases) and at least one additional TFH marker in most cases. Only a minority of cases of MF with large cell transformation (13 cases) were immunoreactive for PD-1, and uniformly negative for CD200. The majority of cases of PTCL, NOS (34/58 cases) were immunoreactive for one or more TFH markers (PD-1 > CD200 > ICOS) with most of them (24/58 cases) showing immunoreactivity for just one follicular T-cell marker and only a minority positive for 2/3 TFH markers (5/58 cases) or 3/3 TFH markers (5/58 cases); the latter group may represent early, evolving angioimmunoblastic lymphoma or another TFH-derived neoplasm. In contrast, non-TFH-derived neoplasms, including T lymphoblastic lymphoma/leukemia (10 cases), T-PLL (11 cases), NK/T cell lymphoma (10 cases), ALCL (33 cases; 16 ALK+ and 17 ALK-), were mostly negative for all TFH markers, with a minority of cases immunoreactive for one TFH marker.

 PD-1 (EH33)CD200ICOS
MF with large cell transformation4/130/125/12

Conclusions: PD-1 expression, along with other TFH markers, identifies at least two unique subsets of T-cell neoplasms and substantiates the model of T-cell neoplasia as a process in which T cells at specific stages of differentiation/activation undergo neoplastic transformation. A panel of TFH immunophenotypic markers is helpful for the further characterization of PD-1+ T-cell neoplasms and identification of TFH-derived neoplasms.
Category: Hematopathology

Monday, March 4, 2013 1:00 PM

Poster Session II # 215, Monday Afternoon


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