Marked effectiveness of low-dose oral methotrexate for steroid-resistant idiopathic hypertrophic pachymeningitis: Case report

Abstract Idiopathic hypertrophic pachymeningitis (HP) is a rare clinical entity characterized by thickening of the dura mater without obvious underlying disease. High-dose steroid therapy is considered to be the first line for idiopathic HP, but half of patients show resistance for steroid therapy and suffer progressive clinical course. We describe low-dose methotrexate (MTX) administration for recurrent and steroid-resistant idiopathic HP resulting in noticeable improvement without severe adverse effects. A 51-year-old Japanese woman with dermatomyositis first presented with right retro-orbital pain caused by dural thickening in the sella and upper clivus involving the right trigeminal nerve, which was diagnosed as idiopathic HP by transsphenoidal biopsy. High-dose methylprednisolone therapy led to remission, and she remained healthy with low-dose dexamethasone. Three years after the initial therapy she presented with right facial nerve and lower cranial nerve palsies caused by diffuse and significant dural thickening in the posterior cranial fossa. Second highdose methylprednisolone therapy was introduced, but the effect was transient and she suffered aspiration pneumonia. Low-dose oral MTX therapy was begun, and her symptoms were almost resolved and dural thickening was remarkably improved without severe adverse effects. Lowdose MTX may be a more appropriate choice for idiopathic HP than steroid administration. Randomized controlled clinical trials are now needed.