A Novel Renal Manifestation in GLIS3-Related Disorder in a Pediatric Patient With Cystic Nephroma.

A 10-year-old Saudi girl with a homozygous GLIS3 gene deletion presented with the classic triad of neonatal diabetes mellitus, congenital hypothyroidism, and congenital glaucoma. During routine surveillance, an incidental complex left renal mass was identified. Comprehensive imaging and histopathological analysis following a core needle biopsy diagnosed a benign multicystic nephroma with features of a mixed epithelial and stromal tumor (MEST). This represents a novel renal manifestation, expanding the phenotypic spectrum of GLIS3-related disorders beyond simple cystic dysplasia. Management favored active surveillance over surgical resection given the lesion's benign nature. The case underscores the necessity for proactive, multidisciplinary, and lifelong monitoring in patients with GLIS3 mutations, who are at risk for evolving multisystem complications, including atypical renal neoplasms, into adolescence and adulthood.