Panretinal Congenital Hypertrophy of the RPE in an 8-Year-Old Girl with an X-Linked STAG2 Mutation

Introduction: Congenital hypertrophy of the retinal pigment epithelium (CHRPE) is a benign proliferation of the melanin-producing retinal pigment epithelium (RPE). Although often a benign and incidental finding, multifocal CHRPE may mimic lesions associated with familial adenomatous polyposis (FAP). Case Description: We describe an 8-year-old girl presenting with optic disc pallor and widespread multifocal bear track CHRPE observed bilaterally on dilated fundoscopy. Fundus autofluorescence (FAF) imaging showed uniform areas of hypoautofluorescence corresponding to the bear track lesions. Spectral domain optical coherence tomography (SD-OCT) demonstrated normal lamination without atrophy. The full-field electroretinogram (ffERG) was within normal limits. Whole-genome sequencing (WGS) revealed a likely pathogenic heterozygous variant in the STAG2 gene (c.3222dup, p.Ser1075IlefsTer12). Conclusions: We present a rare case of bilateral, panretinal bear track CHRPE in a child with a likely pathogenic variant in STAG2. Using multimodal imaging, we contrast bear track lesions of the retina with FAP-associated CHRPE. We also present possible ophthalmic manifestations in carriers of pathogenic STAG2 variants.