Reader response: Lymphoplasmacyte-rich meningioma involving the whole intracranial dura mater

We read the article by Yang et al.¹ that reported lymphoplasmacyte-rich meningioma mimicking the whole intracranial pachymeningitis. We reported immunoglobulin G4 (IgG4) pachymeningitis in a 43-year-old woman who had a history of lymphoplasmacyte-rich meningioma resection in the right middle cranial fossa at age 17, a right orbital granuloma at age 29, and a pulmonary granuloma at age 31.² She then developed left hearing loss and a hypertrophic dura in the posterior fossa at age 35. Six years later, her MRI showed a left frontal meningioma. The biopsied sample showed dense lymphoplasmatic infiltration and IgG4 was stained immunohistochemically. Recently, pachymeningitis was found to relate to IgG4³; so the previously resected samples (meningioma, orbital granuloma, pulmonary granuloma) were restudied and showed positive IgG4 staining. Therefore, our case was a definite IgG4-related pachymeningitis and neurologic symptoms were again improved by steroid therapy. Idiopathic hypertrophic pachymeningitis and lymphoplasmacyte-rich meningioma can be confused on both imaging and histopathologic grounds.⁴ Lymphoplasmacyte-rich meningioma was occasionally reported to spontaneously regress. Its origin, whether neoplastic or inflammatory, is controversial. The case reported by Yang et al. might be IgG4-related; therefore, steroid therapy might be worth a try.