Metanephric Adenoma: A Case Report of a Rare Benign Renal Tumor

Introduction: Metanephric adenoma (MA) is a rare benign kidney tumor with an excellent prognosis, which is usually diagnosed incidentally with no symptoms. The mean age of patients with MA is about 41 years, ranging from 5 months to 83 years in previous studies. Case Presentation: In this study, we present the case of a 29-year-old woman with a diagnosis of MA after nephrectomy. The ultrasound study showed a hyperechoic mass. The intravenous (IV) contrast-enhanced abdominopelvic computed tomography (CT) scan showed a hypodense mass. Based on the results of pathological features and immunohistochemistry (IHC) (positive vimentin, WT1, and PAX8), the diagnosis of MA was established. Conclusions: The diagnosis of MA is commonly based on pathological findings. Therefore, if MA is suspected, renal biopsy, partial nephrectomy, or follow-up of the patient can be used. However, further studies are needed to differentiate MA from papillary renal cell carcinoma and nephroblastoma before taking aggressive measures.