IgG4-related Inflammatory Pseudotumor with Imaging Findings Similar to Meningioma

IgG4-related inflammatory pseudotumor is a feature of IgG4-related disease and develops in various organs. Intracranial IgG4-related inflammatory pseudotumor is rare, and data on the clinical course and response to treatment are insufficient in the literature. We herein report a patient with IgG4-related inflammatory pseudotumor who had magnetic resonance imaging findings similar to meningioma. Tumorectomy was discontinued because of the intraoperative rapid diagnosis, which revealed the infiltration of lymphocytes and plasma cells. She received oral prednisolone therapy for IgG4-related inflammatory pseudotumor, and the tumor size had significantly decreased after six months of treatment.