IgG4-Related Hypertrophic Pachymeningitis Mimicking Cerebral Venous Thrombosis

Immunoglobulin G4-related hypertrophic pachymeningitis (IgG4-RHP) is an increasingly recognized manifestation of IgG4-related disease (IgG4-RD), which is a fibroinflammatory condition that can affect virtually any organ. The three hallmark histopathological features of IgG4-RD are lymphoplasmacytic infiltration of IgG4-positive plasma cells, storiform fibrosis, and obliterative phlebitis. We report a case of biopsy-confirmed IgG4-RHP that was initially misdiagnosed as cerebral venous thrombosis.