IgG4-related inflammatory pseudotumor of the brain parenchyma: a case report and literature review.

A 29-year-old male with a 4-month history of binocular temporal visual field defect, 1-month history of memory loss and 5-day history of headache was admitted to our hospital. Brain MRI showed progressive signal abnormalities in the brain parenchyma. His laboratory tests showed elevated serum IgG4 and liver dysfunction. Abdominal CT, ultrasound and liver biopsy showed chronic liver disease. According to the diagnostic criteria of IgG4-related disease, IgG4-related inflammatory pseudotumor of brain parenchyma was considered. After methylprednisolone treatment, his symptoms improved and brain lesion reduced. This is the second reported case of a tumefactive lesion of the brain with serum IgG4 elevation, which was responsive to steroid treatment. Coincidentally, his mother had similar medical history and imaging findings, and was subspecialty diagnosed with the same disease, but without pathological and immunohistochemical confirmation. This suggests that the disease may be hereditary. It is important to recognize IgG4-related inflammatory pseudotumors of the brain parenchyma so that patients do not undergo unnecessary surgical or other procedures.