Primary angiitis of the central nervous system mimicking a cerebellar tumor.

Primary angiitis of the central nervous system (PACNS), is a rare and poorly understood disease mainly characterized by multifocal segmental inflammation of the small and medium vessels of the central nervous system. Most PACNS are multiple lesions, occurring in the supratentorial subcortical and deep white matter, and only a few cases present as a tumor-like mass lesion. Herein, we describe an extremely rare case of PACNS occurred in the cerebellum, which mimicked a cerebellar tumor. To the best of our knowledge, this is the first reported case of cerebellar tumor-like PACNS proved by histopathological examination.