[1359] Programmed Death-1 (PD-1/CD279) Expression in Bone Marrow Tissue Sections Is Not Specific for Angioimmunoblastic T-Cell Lymphoma (AITL) or T-Cell Lymphomas in General

Christopher H Cogbill, Steven H Swerdlow, Sarah E Gibson. University of Pittsburgh School of Medicine, Pittsburgh, PA

Background: Immunohistochemical (IHC) staining for CD279 is helpful in the diagnosis of peripheral T-cell lymphomas (PTCL) of follicular helper T-cell (TFH) origin, and in particular AITL. However, CD279 expression is not restricted to TFH and some reactive lymph nodes have been reported to have prominent CD279+ cells. It is uncertain if CD279 expression is seen in reactive lymphoid proliferations in the bone marrow (BM) or if it should strongly suggest the presence of AITL or some other type of T-cell lymphoma.
Design: 88 BM biopsy/particle preparation specimens were identified including 10 normal staging BM, 40 with reactive lymphoid aggregates (LA), and 38 with T-cell lymphoma (12 PTCL, NOS; 6 AITL; 6 T-lymphoblastic leukemia; 4 T-cell large granular lymphocytic leukemia (T-LGL); 2 ALK+ anaplastic large cell lymphoma; 2 hepatosplenic T-cell lymphoma; 2 Sezary syndrome; 1 T-cell prolymphocytic leukemia; and 3 other T-cell lymphomas, NOS). The clinicopathologic findings were reviewed and IHC for CD3, CD20, and CD279 were performed. The proportion and intensity of CD279+ cells in LA and in the interstitium were assessed.
Results: 1/10 normal staging BM demonstrated 1-10% scattered weakly CD279+ cells, 7 cases had rare (<1%) weakly CD279+ small lymphocytes, and 2 cases were CD279-. Of 40 cases with reactive LA, 5 had 11-25% scattered weak/variably intense CD279+ cells in LA, 30 had ≤10% scattered weak/variably intense CD279+ cells in LA, 3 had no CD279+ cells in LA with <1% CD279+ interstitial cells, and 2 were CD279-. 6/6 AITL were strongly CD279+ (4 cases 1-25% CD279+, 2 cases >25% CD279+). 1/12 PTCL, NOS with epithelioid histiocyte clusters was strongly CD279+ in >75% of cells, 4 had 11-50% weakly CD279+ cells, 2 showed <1% weakly CD279+ cells, and 5 cases were CD279-. 2/4 T-LGL and 1 other T-cell lymphoma, NOS had a moderate number (11-25%) of weak/variably intense CD279+ cells. The other T-cell lymphomas evaluated contained <1% weakly CD279+ cells or were CD279-.
Conclusions: Although strong CD279 expression in LA should suggest AITL or less often some other type of T-cell lymphoma, weak/variably intense staining even in a moderate number of cells in LA or interstitially is not at all specific for T-cell lymphomas of TFH type and may also be seen in a minority of BM with reactive LA. Recognition of this finding is important to avoid the misclassification of reactive LA as T-cell lymphoma, or categorization of a T-cell lymphoma as being AITL. Conversely, some AITL in BM may have only a minority of CD279+ cells.
Category: Hematopathology

Monday, March 4, 2013 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 207, Monday Morning


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