First Incidence of Extrarenal Wilms Tumor within the Spinal Canal in the Adult Population: A Novel Case Report and Literature Review

Abstract

Background: Wilms tumor (WT), also known as nephroblastoma, is a rare occurrence in adults, accounting for merely 3% of all nephroblastomas or 0.2 cases per million individuals. Extrarenal Wilms tumor (ERWT) emerges outside the renal confines and comprises 0.5 to 1% of all WT cases. Although ERWT is more prevalent in children, its incidence in adults signifies an even rarer incidence. Oncogenic mutations associated with ectopic nephrogenic rests (NR) may contribute to ERWT development. Diagnosis involves surgical resection and pathology examination. Due to scarce cases, adults often rely on pediatric guidelines. We conducted a thorough search on PubMed, Scopus, and Web of Science databases to establish our case's uniqueness. To the best of our knowledge, this is the first documented incidence of extrarenal Wilms tumor within the spinal canal in the adult population. Case presentation: A 22-year-old woman with a history of congenital lipo-myelomeningocele surgery as an infant presented with a 6-month history of back pain. This pain gradually resulted in limb weakness, paraparesis, and loss of bladder and bowel control. An MRI showed a 6x5x3 cm spinal canal mass at the L4-S1 level. Consequently, a laminectomy was performed at the L4-L5 level to remove the intramedullary tumor. Post-surgery histopathology and immunohistochemistry confirmed the tumor as ERWT with favorable histology without any teratomatous component. Conclusion: This report underscores a rare case of ERWT in an adult, challenging conventional diagnostics. Timely surgical intervention is recommended for similar masses, emphasizing the need for further research and clinical awareness.