Metanephric Adenofibroma of the Left Kidney in an Adult Patient

Metanephric adenofibroma is a rare, benign renal neoplasm arising from the embryonic metanephric tissue, which would typically give rise to normal kidney parenchyma. Despite classical presentation in pediatric patients, we present a case of a 29-year-old female with 6 months of intermittent left upper quadrant pain found to have a 3.8cm left renal mass, partially extending into the collecting system of the superior pole. The patient underwent robotic partial nephrectomy, and histopathology confirmed a diagnosis of metanephric adenofibroma with negative surgical margins. The patient had an uneventful recovery, and requires no acute follow-up, given the benign nature of her diagnosis.