目的:分析临床病理特征,血管免疫母细胞性T细胞淋巴瘤(AITL)的分子变化和预后因素。
方法:收集北京大学肿瘤医院病理科确诊的61例AITL患者的临床资料。形态学上,分为Ⅰ型[淋巴组织反应性增生(LRH)样]、Ⅱ型[边缘区淋巴瘤(MZL)样]和Ⅲ型[外周T细胞淋巴瘤,未指定(PTCL-NOS),如]。免疫组织化学染色用于评估滤泡辅助性T细胞(TFH)表型的存在,生发中心(GC)滤泡树突状细胞(FDC)的增殖,霍奇金和里德-斯特恩伯格(HRS)样细胞的存在和大的B转化。在高功率场(HPF)上,用由EB病毒编码的RNA(EBER)原位杂交染色的载玻片对EB病毒(EBV)+细胞的密度进行计数。必要时进行T细胞受体/免疫球蛋白基因(TCR/IG)克隆性和靶向外显子组测序(TES)测试。采用SPSS22.0软件进行统计分析。
结果:形态亚型(%):Ⅰ型占11.4%(7/61);Ⅱ型占50.8%(31/61);Ⅲ型占37.8%(23/61)。83.6%(51/61)病例显示经典TFH免疫表型。具有可变的GC外FDC网状增殖(中位数20.0%);23.0%(14/61)具有HRS样细胞;11.5%(7/61)具有大的B转化。42.6%(26/61)的病例有高EBV计数。57.9%(11/19)TCR+/IG-,26.3%(5/19)TCR+/IG+,10.5%(2/19)为TCR-/IG-,5.3%(1/19)TCR-/IG+。RHOA的TES突变频率为66.7%(20/30),23.3%(7/30)的IDH2突变,80.0%(24/30)为TET2突变,33.3%(10/30)的DNMT3A突变。综合分析分为四组:(1)IDH2和RHOA共变组(7例):6例为Ⅱ型,1例为Ⅲ型;均具有典型的TFH表型;未发现HRS样细胞和大B转化;(2)RHOA单突变组(13例):1例为Ⅰ型,6例为Ⅱ型,Ⅲ型6例,无典型TFH表型5例,HRS样细胞6例,2例B转化较大。反常,1例显示TCR-/IG-,1例带有TCR-/IG+,1例TCR+/IG+;(3)单纯TET2和/或DNMT3A突变组(7例):3例为Ⅱ型,Ⅲ型4例,所有病例均具有典型的TFH表型;2例有HRS样细胞,2例大B转化,和非典型;(4)无突变组(3例),都是Ⅱ型,具有典型的TFH表型,具有显著的GC外FDC增殖,没有HRS样细胞和大B转化。反常,1例为TCR-/IG-。单因素分析证实,较高密度的EBV阳性细胞是总生存期(OS)和无进展生存期(PFS)的独立不良预后因素。(P=0.017和P=0.046)。
结论:具有HRS样细胞的ALTL病例的病理诊断,大的B转化或Ⅰ型转化是困难的。虽然TCR/IG基因重排试验有帮助但仍有局限性。涉及RHOA的TES,IDH2,TET2,DNMT3A可以有力地帮助这些困难病例的鉴别诊断。肿瘤组织中EBV阳性细胞计数的较高密度可能是低存活率的指标。
OBJECTIVE: To analyze the clinicopathological features, molecular changes and prognostic factors in angioimmunoblastic T-cell lymphoma (AITL).
METHODS: Sixty-one cases AITL diagnosed by Department of Pathology of Peking University Cancer Hospital were collected with their clinical data. Morphologically, they were classified as typeⅠ[lymphoid tissue reactive hyperplasia (LRH) like]; typeⅡ[marginal zone lymphoma(MZL)like] and type Ⅲ [peripheral T-cell lymphoma, not specified (PTCL-NOS) like]. Immunohistochemical staining was used to evaluate the presence of follicular helper T-cell (TFH) phenotype, proliferation of extra germinal center (GC) follicular dendritic cells (FDCs), presence of Hodgkin and Reed-Sternberg (HRS)-like cells and large B transformation. The density of Epstein-Barr virus (EBV) + cells was counted with slides stained by Epstein-Barr virus encoded RNA (EBER) in situ hybridization on high power field (HPF). T-cell receptor / immunoglobulin gene (TCR/IG) clonality and targeted exome sequencing (TES) test were performed when necessary. SPSS 22.0 software was used for statistical analysis.
RESULTS: Morphological subtype (%): 11.4% (7/61) cases were classified as type Ⅰ; 50.8% (31/61) as type Ⅱ; 37.8% (23/61) as type Ⅲ. 83.6% (51/61) cases showed classical TFH immunophenotype. With variable extra-GC FDC meshwork proliferation (median 20.0%); 23.0% (14/61) had HRS-like cells; 11.5% (7/61) with large B transformation. 42.6% (26/61) of cases with high counts of EBV. 57.9% (11/19) TCR+/IG-, 26.3% (5/19) TCR+/IG+, 10.5% (2/19) were TCR-/IG-, and 5.3% (1/19) TCR-/IG+. Mutation frequencies by TES were 66.7% (20/30) for RHOA, 23.3% (7/30) for IDH2 mutation, 80.0% (24/30) for TET2 mutation, and 33.3% (10/30) DNMT3A mutation. Integrated analysis divided into four groups: (1) IDH2 and RHOA co-mutation group (7 cases): 6 cases were type Ⅱ, 1 case was type Ⅲ; all with typical TFH phenotype; HRS-like cells and large B transformation were not found; (2) RHOA single mutation group (13 cases): 1 case was type Ⅰ, 6 cases were type Ⅱ, 6 cases were type Ⅲ; 5 cases without typical TFH phenotype; 6 cases had HRS-like cells, and 2 cases with large B transformation. Atypically, 1 case showed TCR-/IG-, 1 case with TCR-/IG+, and 1 case with TCR+/IG+; (3) TET2 and/or DNMT3A mutation alone group (7 cases): 3 cases were type Ⅱ, 4 cases were type Ⅲ, all cases were found with typical TFH phenotype; 2 cases had HRS-like cells, 2 cases with large B transformation, and atypically; (4) non-mutation group (3 cases), all were type Ⅱ, with typical TFH phenotype, with significant extra-GC FDC proliferation, without HRS-like cells and large B transformation. Atypically, 1 case was TCR-/IG-. Univariate analysis confirmed that higher density of EBV positive cell was independent adverse prognostic factors for both overall survival (OS) and progression free survival(PFS), (P=0.017 and P=0.046).
CONCLUSIONS: Pathological diagnoses of ALTL cases with HRS-like cells, large B transformation or type Ⅰ are difficult. Although TCR/IG gene rearrangement test is helpful but still with limitation. TES involving RHOA, IDH2, TET2, DNMT3A can robustly assist in the differential diagnosis of those difficult cases. Higher density of EBV positive cells counts in tumor tissue might be an indicator for poor survival.