EPID-26. The Complex Landscape of Neurofibromatosis Type 1 and Plexiform Neurofibromas in A Highly Consanguineous Population

Abstract INTRODUCTION Neurofibromatosis type 1 (NF1) is a common autosomal dominant genetic disorder characterized by variable clinical expression and a predisposition to tumor development. Plexiform neurofibromas (PNs), a hallmark and often debilitating feature, contribute significantly to morbidity. This study presents a retrospective, single-center analysis of NF1 patients at King Faisal Specialist Hospital & Research Centre (KFSHRC) in Riyadh, Saudi Arabia, focusing on the distribution of PNs and associated comorbidities. METHODS We retrospectively reviewed the records of all patients diagnosed with NF1 at KFSHRC between 2020 and 2025. Data were extracted from electronic medical records, including demographics, family history, NF1 diagnostic criteria, PN presence and distribution, associated comorbidities, and additional tumor types. RESULTS Fifty-one NF1 patients were identified (28 females, 54.9%; 23 males, 45.1%). The most common clinical features included café-au-lait macules (n = 46, 90.2%) and cutaneous neurofibromas (n = 31, 60.8%), with PNs present in 25 patients (49.0%). Other features included skinfold freckling (33.3%), Lisch nodules (21.6%), skeletal abnormalities (13.7%), and optic pathway gliomas (11.8%). Parental consanguinity was noted in 21.6%, and a family history of NF1 in 60.8%. The mean age at NF1 diagnosis was 4.8 years, with PNs typically emerging by 8.2 years. Among PN patients, 44% had multiple tumors. PN distribution involved the extremities (56%), trunk (48%), head (24%), orbit (24%), neck (20%), face (8%), and other regions (12%). Common comorbidities included headache (13.7%), scoliosis (11.8%), epilepsy (9.8%), visual impairment (9.8%), cognitive delay (3.9%), and malignant peripheral nerve sheath tumors (3.9%). Additional tumors included gliomas (n = 5), schwannomas (n = 3), and rhabdomyosarcoma (n = 1). CONCLUSION This cohort of NF1 patients exhibited a high prevalence of plexiform and cutaneous neurofibromas, along with diverse comorbidities and tumor manifestations. These findings underscore the need for early diagnosis, multidisciplinary management, and sustained surveillance to optimize outcomes in this complex patient population.