# Metanephric stromal tumor as a rare differential diagnosis of a renal mass in children – a case report

## TL;DR

A rare case of a benign kidney tumor in a child is described, highlighting how imaging helped distinguish it from a more serious cancer.

## Contribution

This case report provides insights into the radiological features of pediatric metanephric stromal tumors.

## Key findings

- Radiological features like low initial volume and high apparent diffusion coefficient suggested a non-malignant tumor.
- Successful kidney-preserving surgery was performed without chemotherapy.
- Intraoperative contrast-enhanced ultrasound aided in defining tumor margins.

## Abstract

This report presents the case of a benign metanephric stromal tumor that occurred in the kidney of a 5-year-old boy and in which differentiation from a nephroblastoma was successful. Radiological assessment played the decisive role in this case, as the low initial volume, a high apparent diffusion coefficient, and lack of rapid tumor growth were considered atypical for a nephroblastoma. The boy underwent successful kidney-preserving resection without neoadjuvant chemotherapy, and intraoperative contrast-enhanced ultrasound examination helped to accurately define the tumor margins. The case is reported to provide information on the radiological picture of pediatric metanephric stromal tumor.