Objective: To investigate the expression of programmed cell death ligand 1 (PD-L1), clinicopathologic features, immunohistochemical expression and molecular characteristics in fumarate hydratase (FH)-deficient renal cell carcinoma and to explore the potential application of immunotherapy in the patients. Methods: There were six patients with FH-deficient renal cell carcinoma treated at the First Affiliated Hospital of Fujian Medical University between January 2020 and October 2022. The clinical data, histological morphology, immunophenotype, PD-L1 expression and next-generation sequencing results were tabulated and analyzed. Results: There were 6 patients, all male, age ranged from 37 to 72 years (mean 45.7 years). Four cases were high-grade (WHO/ISUP grade3-4) with 2 or more histologic patterns, including papillary (most common), glandular, tubular, vesicular, ethmoid, nest-like, cystic and solid structures. Two cases were low-grade which showed nest-like, glandular, or tubular arrangement with eosinophilic flocculent cytoplasm and small intracellular vacuoles. Immunohistochemical analysis revealed strong expression of 2SC in all 6 cases, negative expression of FH in 5 cases, and positive expression of GATA3 in 5 cases. In high-grade cases, the mean values of CD4 and CD8 positive T-lymphocytes in advanced tumor invasion were 180.3/mm2 and 130.5/mm2, respectively. PD-L1 combined positive scores (CPS) were 20, 50, 5 and 30, respectively. The Ki-67 proliferative index were 20%, 20%, 10% and 30%, respectively. In low-grade cases, the mean values of CD4 and CD8 positive T-lymphocytes were 123.0/mm2 and 100.5/mm2, respectively. The PD-L1 CPS score was 1, and the Ki-67 proliferation index was 3%. High-throughput sequencing showed FH gene somatic mutation in 3 cases, FH gene germline mutation in 2 cases, and FH gene mutation was not detected in one case. Conclusion: FH-deficient renal cell carcinoma is more commonly high-grade than low grade. FH and 2SC are immunohistochemical markers used in the diagnosis of FH-deficient renal cell carcinoma, and GATA3 positivity is supportive of the diagnosis. The tumor infiltration of high-grade FH-deficient renal cell carcinoma shows an increase in CD4 and CD8 positive T-lymphocytes, and high expression of PD-L1; thus, anti-PD-L1 immunotherapy can be used as a treatment option.
目的： 探讨延胡索酸水合酶（FH）缺陷型肾细胞癌的细胞程序性死亡配体1（PD-L1）的表达情况、临床病理特征、免疫组织化学表达及分子特征，探寻免疫治疗在FH缺陷型肾细胞癌中的应用前景。 方法： 对福建医科大学附属第一医院2020年1月至2022年10月收集的6例FH缺陷型肾细胞癌的PD-L1表达情况、临床资料、组织学形态、免疫表型、二代测序基因检测进行总结并随访预后。 结果： 患者均为男性，年龄37~72岁，平均年龄45.7岁。4例高级别FH缺陷型肾细胞癌病例均可见2种或2种以上的结构混杂存在，以乳头状结构最常见，还可见到腺管状、腺泡状、筛状、巢团状、囊性变、实性结构混杂存在，癌细胞WHO/国际泌尿病理协会（ISUP）核分级为3~4级。2例低级别FH缺陷型肾细胞癌病例表现为巢团状、腺管状排列，嗜酸性、絮状胞质及小的胞质内空泡。6例2-琥珀酸半胱氨酸（2SC）均为强阳性，5例FH表达丢失、GATA3阳性，4例高级别病例肿瘤浸润的CD4、CD8阳性的T淋巴细胞平均值分别是180.3/mm2、130.5/mm2，PD-L1联合阳性评分（CPS）分别是20、50、5、30，Ki-67阳性指数分别为20%、20%、10%、30%；2例低级别病例肿瘤浸润的CD4、CD8阳性的T淋巴细胞平均值分别是123.0/mm2、100.5/mm2，PD-L1 CPS评分均为1，Ki-67阳性指数均为3%。高通量测序3例检测到FH基因体系突变，2例检测到FH基因胚系突变，1例未测出FH基因突变。 结论： FH缺陷型肾细胞癌以高级别形态常见，低级别形态少见。FH和2SC是诊断FH缺陷型肾细胞癌特征性的免疫组织化学标志物，GATA3阳性对诊断具有提示作用。高级别FH缺陷型肾细胞癌肿瘤浸润的CD4、CD8阳性的T淋巴细胞增加，PD-L1高表达，抗PD-L1免疫治疗将可作为患者的治疗选择。.