Metanephric Adenoma in the Pediatric Population: Diagnostic Challenges and Follow-up

Abstract Objective To discuss the presenting features, imaging findings, and recommended management of patients with Metanephric adenoma (MA) focusing on the diagnostic challenges and indications for follow up. Materials and Methods In this case report, we present a case of a 10-year-old female with MA who eventually underwent nephron sparing surgery with a partial nephrectomy. We performed a literature review of previous cases of metanephric adenoma and their respective management and follow-up. Results Renal ultrasound demonstrated a heterogeneous, echogenic mass measuring 3.8 cm at the upper pole of the right kidney. Further investigations consisted of computed tomography scan, magnetic resonance imaging, and magnetic resonance angiography. The patient underwent robotic-assisted partial nephrectomy. The immunohistochemical staining pattern, gross, and microscopic appearance of the lesion were consistent with the diagnosis of MA. The combination of CK7, EMA, and S-100 negativity and WT1 and CD57 positivity is considered characteristic of metanephric adenoma as described in the literature. Conclusion MA is a rare benign tumor and especially in the pediatric population can cause significant concern over a possible malignant lesion. Although, no follow-up recommendations currently exist in cases of completely resected MA, we standardly perform postoperative surveillance. Although Metanephric Adenoma is difficult to diagnose preoperatively, given the advances in nephron sparing surgery and the utilization of nonionizing radiation modalities for follow up, we can manage these patients safely and with lower morbidity by preserving renal parenchyma.