Ectopic nephrogenic rests in children: A series of 13 cases in a single institution

Purpose: Ectopic nephrogenic rests (ENR) are extremely rare, and their diagnosis and treatment have not yet been standardized. Our study aimed to analyze the clinical and pathological features of ENR in children and explore the optimal methods for diagnosis and treatment.

Methods: A retrospective, single-center, case series study of 13 children with ENR was performed. Clinical manifestations, work-up, pathological features, and treatment methods were analyzed, and the postoperative status was evaluated at follow-up.

Results: The study cohort included seven males and six females aged 1/4-19 months, who were divided into two subgroups: group 1 (pure ENR, cases 1-3) and group 2 (ENR associated with teratoma, cases 4-13). The patients commonly presented with a painless mass or an incidental finding in surgery. The ENR were detected in the lumbosacral and sacrococcygeal region (five cases), retroperitoneal area (five cases), testis (one case), gubernaculum testis (one case), and stomach (one case). Radiological findings showed a mixed-density mass or a mixed-signal-intensity lesion in group 2. All the patients underwent surgical resection, and all except two were event-free in a follow-up period of 2-154 months. Case 8 showed recurrence, and extended surgery was performed. Case 7 developed metastases and received chemotherapy.

Conclusions: ENR are rare among children and have no specific clinical manifestations, lab tests, and radiological features. Different treatment strategies may be adopted based on the diagnosis. Complete resection can generally be achieved, and the prognosis is excellent in most cases. However, relapse or metastasis may occur in a small subset of patients. Close follow-up is mandatory to detect recurrence and metastasis early.