Metanephric Adenoma in the Pediatric Population- Diagnostic Challenges and Follow-Up

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.

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.

Renal ultrasound demonstrated a heterogeneous, echogenic mass measuring 3.8 cm at the upper pole of the right kidney. Further investigations consisted of CT scan, MRI, and MRA. The patient underwent robotic-assisted partial nephrectomy. The immunohistochemical staining pattern, gross and microscopic appearance of the lesion were consistent with the diagnosis of Metanephric Adenoma (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.

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 post-operative surveillance. Although Metanephric Adenoma is difficult to diagnose preoperatively, given the advances in nephron sparing surgery and the utilization of non-ionizing radiation modalities for follow up, we can manage these patients safely and with lower morbidity by preserving renal parenchyma.

Urology. 2018 Jul 10 [Epub ahead of print]

Michael Benson, Sang Lee, Ratul Bhattacharya, Valentino Vasy, Jamshed Zuberi, Sayeeda Yasmeen, Mutahar Ahmed, Moneer K Hanna

Division of Urology, Rutgers New Jersey Medical School, Newark, New Jersey. Electronic address: ., Saint George's University, Grenada., St. Joseph's Regional Medical Center, Paterson, New Jersey., Department of Pathology, Saint Barnabas Medical Center, Livingston, New Jersey., Department of Urology, Hackensack University Medical Center, Hackensack, New Jersey., Department of Urology, New York-Presbyterian Weill Cornell Medical Center (MKH), New York, New York.