Collision kidney tumor with clear cell renal cell carcinoma and papillary type 1 renal cell carcinoma. A case report and review of the literature

Introduction: The most common renal neoplasms include clear cell, papillary, and chromophobe renal cell carcinomas. The simultaneous occurrence of different histological types of adjacent neoplasms in the same organ is known as a collision tumor. Collision kidney tumors have already been described but only in rare cases. Case description: In this case report we present a 68-year-old man with chronic kidney insufficiency under dialysis who underwent an open right nephrectomy in our department with the histological diagnosis of a collision kidney tumor consisting of clear cell and papillary type 1 renal cell carcinoma. Conclusion: To the best of our knowledge, our case of a collision kidney tumor consisting of clear cell RCC and papillary type 1 RCC, is unique in literature.