[Case report of a 28-year-old male with the rapid progression of steroid-resistant central nervous system vasculitis diagnosed by a brain biopsy].

A 28-year-old Japanese male without a significant past medical history presented with new-onset generalized clonic seizure and headache. A brain MRI revealed multiple enhanced lesions on both cerebral hemispheres. Laboratory exams showed no evidence of systemic inflammation or auto-immune antibodies such as ANCAs. Despite four courses of high-dose methylprednisolone pulse therapy and five treatments with plasmapheresis, his symptoms worsened and the MRI lesions progressed rapidly. During these treatments, we performed a targeted brain biopsy, that revealed histological findings consistent with a predominant angiitis of parenchymal and subdural small vessels. He was provided with diagnosis of central nervous system vasculitis (CNSV). Subsequent cyclophosphamide pulse therapy enabled a progressive successful improvement of his symptoms. While diagnostic methods for CNSV remain controversial, histological findings are thought to be more useful in obtaining a more definitive diagnosis than findings in image studies, such as MRI and angiography. We suggest that a brain biopsy should be considered during the early period of cases with suspected CNSV and rapid clinical deterioration. We also detected human herpesvirus 7 (HHV-7) using PCR technology in brain biopsy specimens, however the relationship between CNSV and HHV-7 infection is unknow.