结膜淋巴上皮癌的临床病理学和基因突变特征

Clinical pathological and genetic mutation characteristics of conjunctival lymphoepithelial carcinoma

目的分析结膜淋巴上皮癌的临床病理学和基因突变特征。方法回顾性病例系列研究。收集2006年1月至2022年12月于天津市眼科医院诊断为结膜淋巴上皮癌且接受肿瘤切除手术的3例患者资料和4份石蜡标本(其中1例患者先后行2次手术),采用免疫组织化学染色方法检测上皮抗原和淋巴细胞性抗原,采用原位杂交方法检测Epstein-Barr病毒(EBV)编码的RNA(EBER),应用二代测序方法对2例患者的3份标本进行全外显子组测序。结果3例患者均为男性,年龄均大于65岁,病程3~44个月。均为单眼发病,肿瘤位于球结膜或角结膜缘,呈红色,肿瘤最大径4~20 mm。影像学检查显示肿瘤位于眼球前方,眶骨、眼外肌、视神经和副鼻窦未受累。所有患者均无局部淋巴结转移。病理表现为未分化癌巢伴有显著的反应性淋巴细胞、浆细胞浸润;肿瘤细胞呈广谱细胞角蛋白、上皮膜抗原、肿瘤蛋白40和肿瘤蛋白63阳性,细胞增殖抗原Ki67增殖指数大于80%;淋巴细胞分化簇20阳性、CD3阳性、CD8阳性;原位杂交显示例1患者的2份标本部分瘤细胞表达EBER。二代测序显示3份标本发生体细胞突变的基因个数分别为58、50和36个,突变基因参与的信号通路富集于黑色素瘤信号通路、缺口蛋白1信号通路和大鼠肉瘤同源物家族Q三磷酸鸟苷酶循环;生化过程富集于氨基酸饥饿后反应,程序性坏死,调控脂类合成、钠离子转运和染色体分离等;3份标本均发生突变的基因是癫痫阈值2(SZT2),并且SZT2参与氨基酸饥饿后反应。1例行部分切除手术后40个月行第2次完整切除手术,另外2例行完整切除手术;3例均未行放射治疗或化学治疗,2例未复发,1例失访。结论结膜淋巴上皮癌伴有明显的淋巴细胞、浆细胞浸润,部分病例与EBV感染有关,结膜淋巴上皮癌存在SZT2等基因突变。

Objective To analyze the clinical pathological and genetic mutation characteristics of conjunctival lymphoepithelial carcinoma.Methods A retrospective case series study was conducted.Data from three patients diagnosed with conjunctival lymphoepithelial carcinoma and treated with tumor resection surgery at Tianjin Eye Hospital from January 2006 to December 2022 were collected.Four paraffin specimens(including one patient undergoing two surgeries)were subjected to immunohistochemical staining for epithelial antigen and lymphocytic antigen.Epstein-Barr virus(EBV)-encoded RNA(EBER)was detected using in situ hybridization,and whole-exome sequencing was performed on three specimens from two patients using next-generation sequencing methods.Results All three patients were males aged over 65,with a disease duration ranging from 3 to 44 months.The tumors were unilateral,located on the bulbar or limbal conjunctiva,appearing red,with a maximum diameter of 4-20 mm.Imaging examinations revealed anterior location of the tumors with no involvement of the orbital bone,extraocular muscles,optic nerve,or paranasal sinuses.No local lymph node metastasis was observed in any patient.Pathological findings included undifferentiated carcinoma nests with significant reactive lymphocytic and plasma cell infiltration.Tumor cells were positive for pan-cytokeratin(CK-pan),epithelial membrane antigen(EMA),tumor protein 40(p40),and tumor protein 63(p63),with a cell proliferation index(Ki67)exceeding 80%.Cluster of differentiation 20(CD20),CD3,and CD8 were positive for lymphocytes.In situ hybridization showed partial tumor cell expression of EBER in two specimens of one patient.Whole-exome sequencing revealed 58,50,and 36 mutated genes in the three specimens,with enriched signaling pathways including melanoma signaling pathway,Notch1 signaling pathway,and RHOQ GTP cycle;enriched biochemical processes included amino acid starvation response,programmed cell death,regulation of lipid synthesis,sodium ion transport,and chromosome segregation.The common mutated gene in all three specimens was SZT2,and SZT2 was involved in the amino acid starvation response.One patient underwent a second complete resection surgery 40 months after partial excision,while the other two underwent complete resection surgery without recurrence.Two patients did not undergo radiation or chemotherapy,and one was lost to follow-up.Conclusions Conjunctival lymphoepithelial carcinoma is associated with prominent lymphocytic and plasma cell infiltration,some cases are associated with EBV infection,and SZT2 mutations are present in conjunctival lymphoepithelial carcinoma.