[A case of rheumatoid factor-positive pachymeningitis].

We report a case of rheumatoid pachymeningitis involving the posterior fossa. A 71-year-old woman presented with headache, vertigo and dizziness. MRI demonstrated hypertrophic masses in the meninges of the left cerebellar tentorium, cerebellopontine angle and the fourth ventricle. Six months of treatment with betamethasone, prednisolone and azathioprine improved the patient's neurological status. Because an inappropriate immune process and systemic immune disease may cause idiopathic pachymeningitis, the performance of immunological studies for idiopathic cases is mandatory.