A case of myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA)-associated hypertrophic pachymeningitis presenting with multiple cranial nerve palsies and diabetes insipidus.

A 61-year-old woman developed hearing difficulties and became thirsty after experiencing cold symptoms. A neurological examination revealed a loss of odor sensation, facial palsy, dysphasia, and dysarthria. Vocal cord palsy was observed during pharyngoscopy. Brain magnetic resonance imaging (MRI) showed a thickened pituitary stalk and swelling of the pituitary gland, but no high signal intensity regions were seen in the posterior portion of the pituitary gland. Gadolinium-enhanced MRI demonstrated a thickened dura mater over the anterior cranial fossa. A biopsy specimen of the thickened dura mater showed fibrosis, granulomatous inflammation, and necrotic foci. Blood tests detected myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA). The patient's urine osmolarity was low even though she exhibited hypernatremia. We diagnosed her with hypertrophic pachymeningitis associated with MPO-ANCA and diabetes insipidus. The patient received two courses of 5-day high-dose intravenous methylprednisolone (1.0 g/day), and was subsequently administered oral prednisolone, which gradually relieved her symptoms. However, the patient's symptoms recurred despite the high-dose prednisolone treatment. It was difficult to control the patient's symptoms in this case with oral prednisolone monotherapy, but combined treatment with cyclosporine resulted in sustained remission. It is considered that patients with MPO-ANCA-positive hypertrophic pachymeningitis require combination therapy with prednisolone and immunosuppressive agents at an early stage.