[Hypertrophic cranial pachymeningitis with propionibacterium acnes detected by dural biopsy].

A 30-year-old woman experienced recurrent dull headache and frequent partial motor seizure (Jacksonian type) that marched from right fingers. This motor seizure was uncontrollable with ordinary anticonvulsant therapy. Cerebrospinal fluid showed mild pleocytosis. Cranial CT examination was unremarkable, but MRI revealed thickened dural lesion on the left fronto-parietal site, giving diagnosis of hypertrophic cranial pachymeningitis. Dural biopsy showed nonspecific chronic granulomatous state without specific granuloma such as tuberculosis nor sarcoidosis. Anaerobic culture revealed Propionibacterium acnes, a rare causative agent of meningitis. We conclude that it is important to follow a case of unknown cause pachymeningitis carefully with MRI, and in some cases, is required a dural biopsy to make a diagnosis before steroid therapy.