Pathological findings of hypertrophic pachymeningitis associated with eosinophilic granulomatosis with polyangiitis

The most common neurological manifestation of eosinophilic granulomatosis with polyangiitis (EGPA), formerly called Churg-Strauss syndrome, is mononeuritis multiplex caused by small-vessel vasculitis. In contrast, central nervous system involvement is rare. Among EGPA-associated central nervous system disorders, there are only a few reported cases of hypertrophic pachymeningitis (HP). Here, we report a patient with EGPA with headache and ophthalmoplegia who presented with HP and had a dural biopsy. The biopsy specimen showed lymphocytic inflammatory cell infiltration without EGPA-specific findings, that is, eosinophilic infiltration, granuloma or angiitis. To the best of our knowledge, there are no previous reports of EGPA-associated HP pathology. Here, we report the first case presentation of a patient with EGPA-associated HP with pathological findings.