Comparison between primary and secondary central nervous system vasculitis in terms of clinical, biochemical, radiological, histopathological features, and outcomes: a single-center retrospective cohort study

Introduction Primary angiitis of the CNS (PACNS) is a rare inflammatory disorder affecting blood vessels of the brain and spinal cord causing acute stroke. This study aimed to describe clinical, biochemical, imaging and histopathological findings of a retrospective single-center PACNS cohort in comparison to a cohort of secondary angiitis of CNS (SACNS). Methods All consecutive patients diagnosed with PACNS or SACNS between 2000 and 2023 were identified using our institutional database. Univariate comparison between both groups and multivariate analysis for independent predictors was performed, as well as Receiving Operating Characteristic analysis for white blood cell count predictive of PACNS. Kaplan–Meier curves were used for evaluating survival outcomes. Results We identified 20 patients in each group. PACNS patients presented more frequently with seizures (40% vs. 5%, p = 0.02) and pseudotumoral lesions (45% vs. 10%, p = 0.014). In PACNS patients, median serum WBC count at diagnosis was lower (8.4×10 3 /mm 3 6.4–9.9 vs. 11.2×10 3 /mm 3 9–13.6 p = 0.027) and 18FFDG-PET/CT ( p = 0.001) was negative in all cases. No significant differences were observed for lumbar puncture profiles and diffusion weighted imaging patterns. Small-vessel vasculitis with a lymphocytic pattern was the most represented histologic phenotype in both groups. Serum WBC count ≤9.93 ×10 3 /mm 3 was the only independent predictor of PACNS using multivariate analysis OR 95%CI 5.107, (1.177–22.159). Both groups did not differ in terms of mortality, relapse and clinical outcome. Conclusion In our study, PACNS patients presented more often with pseudotumoral lesions, seizures and small-vessel involvement and lymphocytic histologic pattern. WBC count ≤9.93×10 3 /mm 3 was an independent predictor of PACNS diagnosis.