Biopsy-proven PACNS: results from the large, multicentre cohort of cerebral vasculitis patients.

Background: Reports of primary angiitis of the central nervous system (PACNS) are mainly restricted to clinically suspected cases, but biopsy-proven ones are rare. Here, we present results from a large multicentre cohort of patients with biopsy-proven PACNS (BP-PACNS). In particular, we provide insights into characteristics and treatment responses of PACNS subtypes.

Methods: BP-PACNS patients treated between 1999 and 2021 were analysed. The outcome was assessed by the modified Rankin Scale (mRS). Between-group comparisons were performed by Kruskal-Wallis, χ² or Fisher's exact tests.

Results: In total, 57 patients were analysed (52% male). Of these, n=37 (65%) had a lymphocytic (L-PACNS), n=9 (16%) an amyloid-beta-related angiitis (ABRA), n=8 (14%) a granulomatous (G-PACNS) and n=3 (5%) a necrotising (N-PACNS) PACNS subtype. At the time of diagnosis, age differed significantly between groups (median age (years) L-PACNS 47, ABRA 64.5, G-PACNS 37, N-PACNS 65; p=0.008). The clinical course was mostly monophasic in L-PACNS and ABRA (65% and 75%, respectively), while relapsing-remitting in G-PACNS (63%). Median mRS at last follow up was 2 (IQR 1.25-4) in the study group. Worst outcome (median mRS 4) and highest mortality (25%) were seen in G-PACNS. Good induction treatment response was achieved in 77% of all BP-PACNS patients but was low in those with G-PACNS (29%).

Conclusions: In this large, multicentre series of BP-PACNS patients, G-PACNS had a worse functional outcome, a predominant relapsing-remitting disease and a poorer response to the induction therapy. An optimal first-line treatment regimen for G-PACNS patients should be further examined and established in larger studies to improve the outcome of G-PACNS patients.