[Teratoid Wilms tumor in an adult: A case report].

Background: Teratoid nephroblastoma, also known as teratoid Wilms tumor, is a histological variant that is rarely described in medical literature, presenting a diagnostic challenge today. This variant is characterized by the presence of tumor cells that show differentiation towards various types of tissues, including mesodermal and ectodermal components, characteristics that make it resistant to the medical therapeutics usually employed, resulting in a gloomier prognosis than typical nephroblastoma. The objective is to highlight the challenges of an unusual pathology in an adult. Clinical case: 21-year-old female patient with a palpable left renal tumor, who underwent radical nephrectomy; the subsequent histopathological analysis reported teratoid nephroblastoma. Conclusions: Due to its low incidence, the diagnosis and treatment of teratoid nephroblastoma are based on the protocols described for the pediatric population by the National Wilms Tumor Study Group (NWTSG)/Children's Oncology Group (COG) and the International Society of Pediatric Oncology (SIOP according to its initialism in French), which together created the UMBRELLA protocol to standardize internationally the diagnosis and treatment of these neoplasms in children. However, due to the rarity in adult populations, these principles also govern management in the older population, with surgical management with neoadjuvant chemotherapy and radiotherapy being a priority.