Clinical and Autoantibody Profile of Systemic Sclerosis Patients in Saudi Arabia: A Single-Center Retrospective Study

Background: Systemic Sclerosis (SSc) is a rare autoimmune disease with significant ethnic and geographic variability. Autoantibody patterns and organ involvement influence prognosis. Data on SSc from Saudi Arabia are scarce. To describe the clinical presentation, autoantibody profile and organ involvement of Saudi SSc patients and to explore associations between autoantibodies and Interstitial Lung Disease (ILD). Methods: We conducted a retrospective observational study at a single tertiary hospital in Saudi Arabia. Adult patients fulfilling the 2013 ACR/EULAR classification criteria for SSc between 2015-2024 were included. Demographic, clinical and serologic data were extracted from medical records. Associations between SSc subtypes, antibody profiles and ILD were analyzed. Results: Twenty-one patients were included (95.2% female; mean age 50.0±13.4 years; mean age at disease onset 33.7±10.4 years). Diffuse cutaneous SSc (dcSSc) accounted for 76.2% and limited cutaneous SSc (lcSSc) for 23.8%. Common manifestations included gastroesophageal reflux disease (95.2%), Raynaud’s phenomenon (90.5%), sclerodactyly (90.5%) and ILD (76.2%). Autoantibodies were frequent: ANA (95.2%), anti-topoisomerase I (ATA, 57.1%) and Anti-Centromere (ACA, 10%). ILD was strongly associated with dcSSc (100% vs. 0% in lcSSc, p<0.001) and trended toward association with ATA positivity (91.7% vs. 8.3%, p = 0.055). All ACA-positive patients (n = 2) were ILD-negative. Conclusion: This first Saudi cohort demonstrates a younger age at diagnosis and a high prevalence of ILD compared to international reports. ATA was associated with ILD, while ACA appeared absent among ILD cases. Given the very small sample size, these findings should be considered hypothesis-generating and warrant confirmation in larger, multicenter studies.