Clivus Inflammatory Pseudotumor Associated with Immunoglobulin G4-Related Disease

Immunoglobulin G4 (IgG4)-related disease is a more recently recognized syndrome. It is characterized by increasing IgG4-positive plasma cells and lymphocyte infiltration. Reports of intracranial pseudotumors associated with IgG4-related disease are very rare. We report a rare case of clivus pseudotumor associated with IgG4-related disease mimicking meningioma.

A 50-year-old man presented with abducens paralysis of the right eye. Brain magnetic resonance imaging revealed a uniformly enhanced mass located in the right upper clivus area, and meningioma was highly suspected. The tumor was totally resected via a retrosigmoid approach craniotomy, which achieved sufficient decompression of the right abducens nerve. Postoperative pathology revealed IgG4-related disease with IgG4 strongly positive on immunohistochemical staining. The patient had no history of autoimmune disease. Postoperative laboratory data revealed no elevation of either IgG (6.94 g/L) or IgG4 (0.131 g/L). Follow-up contrast MRI showed the lesion had disappeared.

Although several cases of intrasellar hypophysitis have been reported, reports of intracranial pseudotumors associated with IgG4-related disease are rare. Special attention is required when the differential diagnosis includes meningioma. Preoperative diagnosis is very important because inflammatory pseudotumors associated with IgG4-related disease could be treated with steroid therapy, avoiding surgery.