Polycystic subdural hygroma associated with immunoglobulin G4-related intracranial hypertrophic pachymeningitis: a case report

Background Recent studies have examined hypertrophic pachymeningitis as an IgG4-RD. However, there are no reports of immunoglobulin G4 (IgG4)-related hypertrophic pachymeningitis with polycystic subdural hygroma. Case presentation A 56-year-old man presented to the hospital with complaints of a persistent, pulsatile, occipital headache and general malaise. Magnetic resonance imaging of the brain revealed hypertrophic pachymeningitis with polycystic subdural hygroma and hematoma. Based on the dural biopsy findings and exclusion of other diseases, the patient was diagnosed with immunoglobulin G4 (IgG4)-related hypertrophic pachymeningitis. IgG4-related diseases may cause subdural hygroma more commonly than other diseases that cause hypertrophic pachymeningitis. Conclusions This is the first case report discussing polycystic subdural hygroma and hematoma with IgG4-related hypertrophic pachymeningitis.