Metanephric adenoma in an 8-year-old child: case report and review of the literature.

Metanephric adenoma (MA) is a renal tumor that is rarely found in children. We present a case of MA that was incidentally discovered in an 8-year-old child on computed tomography. We also review the literature regarding this lesion in the pediatric population. There are certain imaging features of MA that may suggest the diagnosis preoperatively. Metanephric adenoma is often hyperechoic on sonography, hyperdense on noncontrast computed tomography scans, and of low signal intensity on T1- and T2-weighted magnetic resonance images. Nephron sparring surgery has been performed in several cases. However, the distinction of MA from other metanephric lesions as well as from Wilms' tumor and papillary renal cell carcinoma may not be readily apparent at the time of surgery.