MED15::TFE3 fusion renal cell carcinoma with extensive cystic change: A clinicopathologic and molecular genetic study of 2 cases, with an emphasis on differential diagnosis.

Objectives: TFE3-rearranged renal cell carcinomas (RCCs) harbor gene fusions between TFE3 and 1 of many partner genes. MED15::TFE3 fusion RCC is rare, often cystic, and easily misdiagnosed.

Methods: This study aimed to characterize 2 cases of MED15::TFE3 fusion RCC with extensive cystic change using fluorescence in situ hybridization and targeted RNA sequencing.