Eosinophilic vasculitis in an isolated central nervous system distribution.

Eosinophilic vasculitis has been described as part of the Churg-Strauss syndrome, but affects the central nervous system (CNS) in <10% of cases. A 39-year-old woman with a history of migraine without aura presented to an institution in an acute confusional state with concurrent headache and left-sided weakness. Laboratory evaluation showed an increased cerebrospinal fluid (CSF) protein level, but otherwise unremarkable serologies. Magnetic resonance imaging showed bifrontal polar gyral-enhancing brain lesions. Her symptoms resolved over two weeks without residual deficits. Eighteen months later the patient presented with similar symptoms and neuroradiological findings showed involvement of territories different from those in her first episode. Brain biopsy showed transmural, predominantly eosinophilic, inflammatory infiltrates and fibrinoid necrosis without granulomas. She improved when treated with corticosteroids. To our knowledge, this is the first case of non-granulomatous eosinophilic vasculitis isolated to the CNS. No aetiology for this patient's primary CNS eosinophilic vasculitis has yet been identified.