Intracranial Inflammatory Pseudotumors Associated with Immunoglobulin G4-Related Disease Mimicking Multiple Meningiomas: A Case Report and Review of the Literature.

BACKGROUND: Immunoglobulin G (IgG)4-related disease is a syndrome that forms inflammatory pseudotumors with increasing IgG4-positive plasma cells and lymphocytes infiltrating the exocrine gland and other organs. The concept of this disease gradually has gained more recognition. However, reports of intracranial pseudotumors associated with IgG4-related disease are very rare. The purpose of this report is to provide further information helpful in distinguishing IgG4-related disease from multiple meningiomas.

CASE DESCRIPTION: We report a case of a 62-year-old man who presented with visual disturbance and quadrantanopia of the right eye. Magnetic resonance imaging revealed uniformly enhancing masses located near the right paraclinoid at the right Meckel's cave and along the left foramen magnum. He had experienced autoimmune pancreatitis 7 years previously, and the condition had responded to steroid therapy. Laboratory data revealed elevation of IgG (1877 mg/dL) and IgG4 (405 ng/dL). The right paraclinoidal lesion causing visual disturbance was subtotally removed, which provided sufficient decompression of the right optic nerve. IgG4 was strongly positive on immunohistochemical staining, and we started oral corticosteroid medication. Consequently, all lesion masses shrank remarkably within 1 month.

CONCLUSION: There have been a growing number of reports of such multiple pseudotumors associated with IgG4-related disease. In differential diagnosis, this disease entity requires special attention when multiple dural-based tumors are observed. Preoperative presumption is very important because this disease is likely to respond to steroid therapy.