[Progressively transformed germinal center-like follicular T-cell lymphoma:a clinicopathological analysis of 14 cases].

Objective: To investigate the clinicopathologic features of progressively transformed germinal center-like follicular T-cell lymphoma (PTGC-like FTCL). Methods: The clinicopathologic data of 14 PTGC-like FTCL cases that were diagnosed at the Beijing Friendship Hospital Affiliated to the Capital Medical University from January 2017 to January 2022 were retrospectively collected. Clinicopathological features, immunophenotype, and Epstein-Barr virus (EBV) infection status were analyzed in these cases. Polymerase chain reaction (PCR) was performed to detect the clonal gene rearrangements of T cell receptor (TCR) and the immunoglobulin (Ig) in 10 and 8 cases, respectively. Results: The male to female ratio was 5∶2. The median age was 61 years (range 32-70 years). All patients had lymphadenopathy at the time of diagnosis. By using the Ann Arbor system staging, seven cases were classified as stage Ⅰ-Ⅱ, and seven cases as stage Ⅲ-Ⅳ. Seven cases had B symptoms, four cases had splenomegaly, and two cases had skin rash and pruritus. Previously, three cases were diagnosed as classic Hodgkin's lymphoma, three cases as small B-cell lymphoma, two cases as atypical lymphoid hyperplasia unable to exclude angioimmunoblastic T-cell lymphoma (AITL), one case as EBV-associated lymphoproliferative disorder, and one case as peripheral T-cell lymphoma (PTCL) associated with the proliferation of B cells. All the 14 cases showed that the large nodules were composed of mature CD20+, IgD+B lymphocytes admixed with small aggregates of neoplastic cells with pale to clear cytoplasm. Moreover, hyperplastic germinal centers (GCs) and Hodgkin/Reed-Sternberg-like (HRS-like) cells were seen within these nodules in two and five cases, respectively. The neoplastic cells expressed CD3 (14/14), CD4 (14/14), PD1 (14/14), ICOS (14/14), CD10 (9/14), bcl-6 (12/14), CXCL13 (10/14), and CD30 (10/14). The HRS-like cells in five cases expressed CD20 (2/5), PAX5 (5/5), CD30 (5/5), CD15 (2/5), LCA (0/5), OCT2 (5/5) and BOB1 (2/5). Moreover, neoplastic T cells formed rosettes around HRS-like cells. EBV-encoded RNA (EBER) in situ hybridization showed scattered, small, positive bystander B lymphocytes in 8/14 cases, including 3/5 cases containing HRS-like cells. All tested cases (including five with HRS-like cells) showed monoclonal TCR gene rearrangement and polyclonal Ig gene rearrangement. Conclusions: PTGC-like FTCL is a rare tumor originated from T-follicular helper cells. It could be distinguished from angioimmunoblastic T-cell lymphoma by the formation of follicular structure, and lack of follicular dendritic cell proliferation outside the follicles and the polymorphous inflammatory background. In addition, it should be differentiated from lymphocyte-rich classical Hodgkin's lymphoma and low-grade B cell lymphoma.目的： 探讨进行性转化生发中心样滤泡T细胞淋巴瘤（PTGC样FTCL）的临床病理学特征。 方法： 收集首都医科大学附属北京友谊医院病理科2017年1月至2022年1月14例PTGC样FTCL，分析其临床特征、病理形态、免疫表型及EB病毒感染状态。对10例行T细胞受体基因检测，对8例行免疫球蛋白（Ig）基因克隆性检测。 结果： （1）患者男性10例，女性4例，男女比为5∶2，发病年龄32~70岁，中位年龄61岁，起病时均有淋巴结肿大，按Ann Arbor系统分期，Ⅰ~Ⅱ期7例，Ⅲ~Ⅳ期7例，有B症状者7例，脾肿大者4例，伴皮疹及皮肤瘙痒者2例。10例获得原单位病理报告，3例诊断为小B细胞淋巴瘤，3例诊断为经典霍奇金淋巴瘤，2例诊断为不除外血管免疫母细胞性T细胞淋巴瘤（AITL），1例诊断为EB病毒相关淋巴组织增生性病变，1例诊断为外周T细胞淋巴瘤（PTCL）伴多量B细胞反应。（2）形态学显示由形态成熟的小淋巴细胞构成的深染大结节，结节内可见散在及灶状分布的异型瘤细胞，胞质淡染或透明。2例在深染结节内见增生的生发中心。5例在结节内还见到散在霍奇金（HRS）样大细胞。（3）免疫组织化学染色结果显示构成深染大结节的小淋巴细胞表达CD20、PAX5和IgD，胞质淡染或透明的异型细胞表达CD3（14/14）、CD4（14/14）、PD1（14/14）、ICOS（14/14）、CD10（9/14）、bcl-6（12/14）和CXCL13（10/14）；10例（10/14）瘤细胞表达CD30。5例有HRS样大细胞的病例，HRS样大细胞不表达CD3和白细胞共同抗原（LCA），表达CD20（2/5）、PAX5（5/5）、CD30（5/5）、CD15（2/5）、OCT2（5/5）及BOB1（2/5），并见肿瘤性滤泡辅助T细胞包绕HRS样细胞形成花环结构。（4）EB病毒编码的RNA（EBER）原位杂交显示14例中8例见散在较小的B细胞阳性，包括3/5例具有HRS样大细胞的病例，同时显示HRS样细胞阳性。（5）10例病例（包括5例有HRS样大细胞的病例）行T细胞受体基因重排检测均呈单克隆性，8例（包括5例有HRS样大细胞的病例）行Ig基因重排检测均呈多克隆性重排。 结论： PTGC样FTCL是少见的起源于滤泡辅助T细胞的肿瘤，和AITL的鉴别在于前者形成滤泡结构，缺乏滤泡外的滤泡树突细胞网增生和多形性浸润。该病还需和淋巴细胞丰富的经典霍奇金淋巴瘤及低级别B细胞淋巴瘤鉴别。.