[Clinicopathological and molecular genetic characteristics of ELOC mutated renal cell carcinoma].

Objective: To investigate the clinicopathological features, molecular genetic features, differential diagnosis and prognosis of ELOC mutated renal cell carcinoma. Methods: From January 2015 to June 2022, 11 cases of renal cell carcinoma with clear-cell morphology, expression of CAⅨ and CK7 and no 3p deletion were collected. Two cases of ELOC mutant renal cell carcinoma were diagnosed using whole exome sequencing (WES). The clinical features, morphology, immunophenotype, FISH and WES results were analyzed. The relevant literature was reviewed. Results: The two patients were both male, aged 29 and 51 years, respectively. They were both found to have a renal mass by physical examination. The maximum diameters of the tumors were 3.5 cm and 2.0 cm, respectively. At the low magnification, the tumors were well-defined. The tumor cells showed a pushing border and were separated by thick fibrous bands, forming nodules. The tumor cells were arranged in a variety of patterns, including tubular, papillary, solid nest or alveolar. At high magnification, the tumor cells were large, with well-defined cell borders and clear cytoplasm or fine eosinophilic granules. CAⅨ was diffusely box-like positive in both cases. Case 1 was partially and moderately positive for CK7, strongly positive for CD10, diffusely and moderately positive for P504S, and weakly positive for 34βE12. In case 2, CK7 and CD10 were both partially, moderately positive and P504s were diffusely positive, but 34βE12 was negative. FISH results showed that both cases had no 3p deletion. ELOC c.235T>A (p.Y79N) mutation was identified using WES in case 1, while ELOC c.236_237inv (p.Y79C) mutation was identified in case 2. Conclusions: As a new clinical entity, ELOC mutated renal cell carcinoma may be underdiagnosed due to its overlap with clear cell renal cell carcinoma in morphology and immunophenotype. The diagnosis of renal cell carcinoma with ELOC mutation should be confirmed by morphology, immunohistochemistry, FISH and gene mutation detection. However, more additional cases are needed to explain its biological behavior and prognosis.目的： 探讨ELOC突变肾细胞癌的临床病理、分子遗传学特征、鉴别诊断及预后。 方法： 收集2015年1月至2022年6月具有透明形态、弥漫表达碳酸酐酶Ⅸ（CAⅨ）及表达不同程度细胞角蛋白（CK）7但无3p缺失的肾细胞癌11例，通过全外显子测序（whole exome sequencing，WES）诊断为ELOC突变肾细胞癌的患者2例，对其临床特征、形态学、免疫表型、荧光原位杂交（FISH）及全外显子测序结果进行分析，并复习相关文献。 结果： 2例ELOC突变肾细胞癌患者均为男性，年龄分别为29和51岁，临床无明显症状，均为体检发现肾脏占位。肿瘤最大径分别是3.5 cm和2.0 cm。低倍镜下肿瘤与周围组织界限较清楚，呈推挤性生长，被粗大的纤维分隔呈结节状，肿瘤细胞排列方式多样，呈管状、乳头状、实性巢团状或腺泡状；高倍镜下肿瘤细胞体积大，胞质透亮或含有细小的嗜酸性颗粒，细胞界限较清。2例患者肿瘤细胞CAⅨ均呈弥漫“盒状”阳性，病例1 CK7部分中等强度阳性、CD10部分强阳性，P504s弥漫中等强度阳性，34βE12局限性中等强度阳性；病例2 CK7、CD10部分中等强度阳性，P504s弥漫中等强度阳性，34βE12阴性。荧光原位杂交检测结果显示2例均未见3p缺失。病例1全外显子测序结果为ELOC c.235T>A（p.Y79N）突变，病例2全外显子测序结果发现ELOC c.236_237inv（p.Y79C）突变，2例术后随访均未见复发或转移。 结论： ELOC突变肾细胞癌作为一种临床新分类，由于其与透明细胞肾细胞癌的形态学与免疫表型高度重叠，临床可能存在低诊断。在临床病理诊断中，对于ELOC突变肾细胞癌，需综合形态学、免疫组织化学染色、FISH检测及基因突变检测确诊，需要更多的病例积累来阐释其生物学行为及预后。.