Incidental Adult Optic Pathway Glioma and Cerebral Venous Aneurysm in Neurofibromatosis Type 1 With Prior Synovial Sarcoma: A Multidisciplinary Challenge.

Neurofibromatosis type 1 (NF1) is a multisystemic disorder predisposing to various neoplasms and vasculopathies. While optic pathway gliomas (OPGs) are hallmarks of pediatric NF1, their incidental discovery in adults, especially when associated with persistent unidentified bright objects (UBOs), mesenchymal malignancies, and rare venous anomalies, is exceptional. A 49-year-old female with NF1 and a history of cervical synovial sarcoma underwent routine oncological surveillance. Brain MRI incidentally revealed a WHO Grade 1 OPG, multiple persistent UBOs in the brainstem and cerebellar peduncles, and a focal parietal venous aneurysm. Despite being asymptomatic, multimodal ophthalmological imaging was performed. Optical coherence tomography (OCT) showed significant asymmetric axonal loss. The left eye (OS) exhibited marked peripapillary retinal nerve fiber layer (pRNFL) thinning (69 µm, p < 0.01). Notably, while the right eye (OD) had normal pRNFL thickness (83 µm), macular ganglion cell layer (GCL) analysis detected early focal neuro-retinal suffering (54 µm minimum thickness). Automated perimetry confirmed functional correlation in both eyes. This case highlights the "multi-tumor challenge" in NF1, suggesting a high-penetrance phenotype driven by RAS/MAPK hyperactivation. The persistence of UBOs into the fifth decade and the discovery of a rare venous aneurysm likely due to medial dysplasia underscore a unique systemic vasculopathy. Unlike sporadic adult OPGs, NF1-associated forms often follow an indolent course, justifying a "watch-and-wait" strategy. Managing complex adult NF1 phenotypes requires a multidisciplinary approach. This case demonstrates that GCL-OCT can serve as a sensitive "early warning system" for axonal loss before clinical symptoms arise, facilitating non-invasive surveillance in genetically vulnerable individuals.