A subset of renal cell carcinomas harbor gene fusions, and we report the first case of an EZR-ROS1 fusion in renal cell carcinoma. A 47-year-old female presented with hematuria and a mass involving the renal pelvis. Renal biopsy revealed a tumor with solid and tubular architecture that was diffusely positive for PAX8, CK7, and vimentin; retained expression of INI1; focally positive for P504S; and negative for GATA3 and TFE3. Partial nephrectomy was performed, and histologically, the tumor had solid and tubular architecture with mucin-like content within tubules. The nuclei corresponded to WHO/ISUP grade 2 and 3. The morphology was neither specific nor diagnostic, and a final diagnosis of unclassified renal cell carcinoma with solid and tubular architecture was rendered. Molecular sequencing revealed an EZR-ROS1 fusion: a fusion that has never been reported in renal cell carcinoma. Recognition of this fusion is of significance if the tumor becomes metastatic as treatment with crizotinib may be considered.

肾细胞癌的一个子集含有基因融合，我们报告了第一例肾细胞癌中EZR-ROS1融合的病例。一名 47 岁女性出现血尿和累及肾盂的肿块。肾活检显示肿瘤呈实性管状结构，PAX8、CK7 和波形蛋白呈弥漫阳性；保留 INI1 的表达；P504S 局部阳性；GATA3 和 TFE3 为阴性。进行了部分肾切除术，组织学上，肿瘤具有实性和管状结构，小管内含有粘蛋白样内容物。细胞核对应于 WHO/ISUP 2 级和 3 级。形态既无特异性也无诊断性，最终诊断为具有实性和管状结构的未分类肾细胞癌。分子测序揭示了一个EZR-ROS1融合：在肾细胞癌中从未报道过的融合。如果肿瘤发生转移，则识别这种融合具有重要意义，因为可以考虑使用克唑替尼治疗。