Abstract <p>Background Giant retroperitoneal ganglioneuromas (GNs) with lumbar nerve root involvement are extremely rare in children and pose significant diagnostic and surgical challenges. GNs are benign tumors of neural crest origin that can occasionally grow to a considerable size and extend from the spinal canal into the retroperitoneum, mimicking more aggressive lesions. Methods We present a case of a 12-year-old boy with a giant GN arising from the right L4–L5 neural foramen and extending into the psoas muscle and anterior abdominal wall. Preoperative imaging revealed a large, well-defined, dumbbell-shaped mass with punctate calcifications and heterogeneous enhancement. Total tumor resection was achieved through a staged multidisciplinary approach involving spinal hemilaminectomy with instrumentation and transabdominal resection of the tumor. Histopathological analysis confirmed the diagnosis of GN, revealing mature ganglion and Schwann cells with no evidence of malignancy. To contextualize this case, a systematic review of the literature was conducted in accordance with the PRISMA guidelines, identifying three additional pediatric cases that met the criteria for lumbar GNs larger than 10 cm with combined intraspinal and retroperitoneal extension. ResultsAcross cases, common features included scoliosis, radicular symptoms, and characteristic imaging findings, such as foraminal widening and vertebral remodeling. All patients underwent staged surgical resections with favorable outcomes and no recurrence at the follow-up. ConclusionThis report underscores the importance of recognizing the distinctive imaging features of giant lumbar GNs and highlights the role of multidisciplinary surgical management in achieving complete resection and optimal neurological outcomes in pediatric patients.</p>