Objective: To explore the clinicopathological characteristics, immunophenotype, diagnosis and differential diagnosis of renal mucinous tubular and spindle cell carcinoma (MTSCC), and to explore the all-exon mutations, microsatellite stability and tumor mutational burden (TMB) in MTSCC cases. Methods: The data of 5 patients with MTSCC that were submitted to the Department of Pathology, First Affiliated Hospital of Soochow University, China from January 2008 to May 2020, were reviewed and analyzed. The whole exome sequencing (WES) was conducted in all patients, while 3 of them were subject to the analyses of microsatellite stability and TMB. Results: Among the 5 patients, 3 were males and 2 were females. They were 37-76 years old. The maximum diameter of the tumor was 3.5-6.0 cm. The borders of the tumors were well defined. Microscopically, MTSCC was characterized by tubular structure, spindle cell and mucinous stroma, and the nuclear grade of tumor cells was overall low. The average follow-up was 15 months, and no recurrence or metastasis was found. Immunohistochemistry showed that all 5 cases were positive for broad-spectrum cytokeratin (CKpan), cytokeratin (CK)7, CK19, vimentin, PAX8, and P504s (varying expression levels), and the Ki-67 positive index was low. The WES of 5 cases showed that NF2 and PTPN14 exhibited higher mutation rates, which were 3/5 and 2/5, respectively. The microsatellite stability analysis indicated that the 3 cases were all microsatellite stable, and the TMB analysis showed that the TMB of the 3 cases were all <9 mut/Mb. Conclusions: MTSCC is a unique, low-grade pleomorphic kidney tumor. The WES analyses suggest that NF2 and PTPN14 have a higher mutation rate, indicating that the occurrence and development of MTSCC may be closely related to the Hippo pathway. The analysis of microsatellite stability indicates that there is no significant relationship between microsatellite stability and MTSCC, and the TMB analysis suggests that MTSCC patients may not benefit from immunotherapy.
目的： 探讨肾黏液样小管状和梭形细胞癌（MTSCC）的临床病理学特征、免疫表型、诊断及鉴别诊断，探索MTSCC全外显子突变、微卫星稳定性及肿瘤突变负荷（TMB）情况。 方法： 回顾性分析苏州大学附属第一医院病理科2008年1月至2020年5月存档的5例MTSCC患者的临床影像学、病理形态学资料、免疫组织化学表达，对5例MTSCC病例行全外显子组测序，并对其中3例MTSCC病例行微卫星稳定性及TMB分析。 结果： 5例患者中男性3例，女性2例，年龄37~76岁，肿瘤最大径3.5~6.0 cm，界限清楚，镜下以小管结构、梭形细胞及黏液样间质为特征，肿瘤细胞核级别低，细胞异型性小，偶有核仁，核分裂象罕见。术后随访平均15个月，均未发现复发和转移。免疫组织化学显示5例患者广谱细胞角蛋白（CKpan）、细胞角蛋白（CK）7、CK19、波形蛋白、PAX8、P504s均有不同程度的表达，Ki-67阳性指数均较低。5例MTSCC的全外显子组测序结果显示NF2、PTPN14基因表现出较高的突变比例，分别为3/5和2/5。微卫星稳定性分析结果提示3例MTSCC均为微卫星稳定型（MSS），TMB分析结果显示3例MTSCC的TMB均<9 mut/Mb。 结论： MTSCC是一种独特的、低度恶性的多形性肾脏肿瘤。全外显子组测序结果提示NF2、PTPN14基因存在较高的突变率，提示MTSCC的发生发展可能与Hippo通路密切相关。微卫星稳定性分析提示微卫星稳定性与MTSCC的发病无明显关系，TMB结果提示MTSCC患者在免疫治疗中获益的优势不明显。.