Tumor de colisión renal: un caso inusual de carcinoma de células renales y leiomiosarcoma renal

purpose: a collition tumor is characterized by the coexistence of two histologically different neoplasms that are independent of any interface mixing. kidney collition tumors are extremely rare. material and methods: we present the case of a patient diagnosed of a kidney collition tumor consisting of renal cell carcinoma and renal leiomyosarcoma. results: the clinical management of this patient was complex due to the limited experience in the treatment of his kind of tumors, and to the poor results obtained with systemic treatment of the two types of tumors involved. conclusions: there are very few communications about collition tumors of the kidney, and we consider interesting to repot the existence of these tumors as well as their clinical complexity.