Metanephric adenofi broma: Robotic partial nephrectomy of a large Wilms' tumor variant

Purpose: A case of the rare, benign, Wilms' tumor (WT)variant, metanephric adenofi broma (MAF), is presented. Materials and methods: The patient is a 21-yearold female with an incidentally discovered enhancing renal mass. The diagnosis, workup and treatment are outlined. Results: The 19 cm renal mass was ultimately resected via robot-assisted partial nephrectomy. Pathologic diagnosis at our institution was confi rmed as a MAF by the National Wilms' Tumor Study Group (NWTSG).Conclusion: Diffi cult to differentiate from WT, it is imperative that MAF be recognized and appropriately diagnosed because unlike adult WT, the natural history of MAF is indolent and adjuvant chemo/radiation therapy is rarely necessary. This case reinforces the importance of review of potential WT variants by the NWTSG.