Diagnostic Clues That Differentiate Angioimmunoblastic T Cell Lymphoma from “T Zone Dysplasia”, a Type of Atypical Interfollicular Hyperplasia
Tomoko Miyata, Naoko Asano, Shigeo Nakamura. Nagoya University Hospital, Nagoya, Japan
Background: Because angioimmunoblastic T cell lymphoma (AITL) is now diagnosed using immunohistochemistry for markers of follicular helper T cells, more cases of AITL have been recognized than were previously thought to occur. Atypical interfollicular T cell proliferation is sometimes encountered, which is suggestive but not diagnostic of AITL. We refer to such as T zone dysplasia (TZD), but its pathogenesis and relationship to AITL has not been clarified.
Design: Fifteen cases of TZD from our consultation archives were reviewed. Clinical data and histological and immunohistochemical findings were retrospectively analyzed, and rearrangement of the T cell receptor (TCR) was examined using PCR. Nineteen cases of AITL patterns 1 and 2 (AITL-p1,2) were also analyzed for comparison.
Results: TZD was frequent in elderly men (median age, 69 years; male to female ratio, 3:2). It was characterized by localized nodular disease (58%), no B symptoms (90%), anemia (31%), a low platelet count (62%), hyperglobulinemia (44%), an elevated LDH level (46%), an elevated sIL2R level of >2000 U/ml (45%), and chromosomal abnormalities (55%). TZD shared many features with AITL-p1,2 but was more localized and presented with rarer B symptoms and lower sIL2R levels. Histologically, clear cell or large cell proliferation was not observed in TZD. The frequencies of CXCL13 positivity, follicular dendritic cell proliferation, and epithelioid cell/histiocyte proliferation were less than in AITL-p1,2 (p = 0.0003, p = 0.001, and p = 0.02, respectively). PD1 positivity, vascular proliferation, inflammatory background, and presence of EBER+ cells were similar between TZD and AITL-p1,2. Some patients showed TCR rearrangement (5 clonal, 2 restricted, 4 polyclonal, 2 not estimated, and 2 not analyzed). Most patients received no treatment or steroid therapy only. One patient died of follicular lymphoma, but the others for whom information was available were alive without disease progression.
Conclusions: TZD leads a self-healing clinical course despite it sharing many features with AITL. To avoid overtreatment, the clinical and histological clues presented here may be helpful. The presence of EBER+ cells suggests background immunological impairment. It is assumed that abnormal T-cell proliferation in the lymph node causes various laboratory test abnormalities. Further studies of larger numbers of cases are required to confirm the clinicopathological features of TZD and further elucidate its pathogenesis.
Monday, March 4, 2013 1:00 PM
Poster Session II # 218, Monday Afternoon