[A case of idiopathic hypertrophic cranial pachymeningitis presenting as chronic subdural hematoma].

A 26-year-old male presented with a 6-day history of paroxysmal headache which was worsen with nausea and vomiting for 1 day. Head CT on admission revealed left chronic subdural hematoma with midline shift. An emergency Burr hole drainage for hematoma was performed. Headache recurred 6 days later. MRI of the brain revealed a diffuse thickening and a gadolinium-enhancement of the falx, cranial dura mater and tentorium cerebelli on the left side with pia mater involved. Lumber puncture showed increased intracranial pressure and elevated IgG level in cerebrospinal fluid. Histological examination of the biopsy specimen showed thickened, fibrotic dura with a sterile chronic inflammation. According to pathological examination, idiopathic hypertrophic cranial pachymeningitis was considered as the final diagnosis. Symptoms were improved with steroid pulse therapy.