Surgical management and molecular diagnosis of pediatric cystic nephroma: a single-center case series with implications for DICER1 syndrome surveillance.

BACKGROUND: Pediatric cystic nephroma (pCN) is a rare renal neoplasm associated with DICER1 mutations. This study investigates the clinical characteristics, molecular profiles, and surgical outcomes of pCN, emphasizing the transition from isolated tumor resection to systemic syndrome management. CASE DESCRIPTION: We retrospectively analyzed 5 patients with pCN treated between November 2020 and November 2024. Clinical data, imaging, surgical approaches (including robot-assisted laparoscopy), pathological findings, and genetic results were reviewed. The cohort comprised 3 males and 2 females, with a median age of 13 months (range, 7-86 months). Three patients were asymptomatic, with tumors detected incidentally during routine examinations (including one prenatal diagnosis at 6 months gestation); the remaining two presented with palpable abdominal masses. Radiological assessment confirmed multilocular cystic architecture in all cases. Surgical management was tailored to preoperative imaging characteristics and intraoperative findings, consisting of 2 open radical nephrectomies, 1 open partial nephrectomy, and 2 robot-assisted laparoscopic partial nephrectomies. Pathology confirmed pCN in all cases. Comprehensive genetic testing revealed paired germline and somatic DICER1 mutations in every patient. At a mean follow-up of 50.2 months, all patients maintained normal renal function. Of the 5 children, 4 showed no evidence of residual or recurrent tumor. One patient was found to have a small amount of residual tumor postoperatively, which remained stable without significant progression during the follow-up period. Notably, two patients developed thyroid nodules during surveillance. CONCLUSIONS: pCN is a rare entity associated with DICER1 gene mutations. Surgical resection remains the primary treatment modality; notably, partial nephrectomy is a feasible approach even for large tumors with an intact capsule. The diagnosis of pCN mandates lifelong multidisciplinary surveillance for associated neoplasms.