ABSTRACT NUMBER: ESOC2026A2288 PATIENT- AND DISEASE CHARACTERISTICS AND PHARMACOLOGICAL APPROACHES IN PRIMARY ANGIITIS OF THE CENTRAL NERVOUS SYSTEM (PACNS): REPORT OF TWENTY-FIVE DUTCH CASES

Abstract Background and aims Primary angiitis of the central nervous system (PACNS) is a rare, severe form of vasculitis limited to the brain, spinal cord and meninges. We evaluated patient- and disease characteristics, our pharmacological approach and outcome in patients with PACNS. Methods In a retrospective, single-center cohort study, we analyzed consecutive adult patients who met the diagnostic criteria for PACNS. Patients were diagnosed between January 2006 and December 2025 in a tertiary hospital in the Netherlands. Baseline characteristics, mortality, relapse and functional outcome using the modified Rankin Scale (mRS) were assessed. Results We included 25 patients (13 female [52%], median age of 46 years [IQR 39-56]), who had a median follow-up duration of 28 months (IQR 14-74). Diagnosis was biopsy-proven in three cases (12%), the remaining patients (88%) were diagnosed based on MRI, angiography and/or cerebrospinal fluid (CSF). The median time from initial symptoms to diagnosis was 4 months (IQR 1-11). CSF analysis was abnormal in 19 of 22 (86%) patients. Cranial MRI showed abnormalities in all patients, mostly ischemic (64%) and/or gadolinium-enhanced lesion(s) (52%). Additional vessel wall imaging (11/25 patients) showed vessel wall enhancement in 73%, mostly concentric (in 75%). Twenty-two patients (88%) received glucocorticoids as induction treatment, combined with cyclophosphamide in 6 patients (24%). Of all patients, 3 (12%) died, 9 (36%) had a poor outcome (mRS 3-6 at last follow-up), and 11 (44%) relapsed. Conclusions This first Dutch cohort underlines the severity of PACNS, with frequent relapses and significant mortality despite treatment. Conflict of interest Kim Mahabali: nothing to disclose.