Metanephric adenofibroma: robotic partial nephrectomy of a large Wilms' tumor variant.

PURPOSE

A case of the rare, benign, Wilms' tumor (WT) variant, metanephric adenofibroma (MAF), is presented.

MATERIALS AND METHODS

The patient is a 21-year-old 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 confirmed as a MAF by the National Wilms' Tumor Study Group (NWTSG).

CONCLUSION

Difficult 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.