Focal IGG4-Related Hypertrophic Pachymeningitis in the Clivus Completely Cured by Surgery and Glucocorticoid Treatment

Although IgG4-related hypertrophic pachymeningitis is being increasingly recognized, no consensus has yet been reached about an optimal diagnostic and therapeutic approach. When hypertrophic pachymeningitis demonstrates a focal mass, it is difficult to distinguish it from a tumor, such as a meningioma and/or solitary fibrous tumor, preoperatively. We report here a rare case of focal IgG4-related hypertrophic pachymeningitis in the clivus region. A 51-year-old male was admitted to our hospital complaining of bilateral abducens nerve palsies. Magnetic resonance imaging disclosed a symmetrical mass lesion in the clivus region. Homogenous enhancement was evident after contrast medium administration, and the mass lesion had retracted the pons. Cerebral angiography revealed staining via the bilateral meningohypophyseal trunk. The lesion was preoperatively diagnosed as a clivus meningioma. The patient underwent surgical excision via a left side anterior petrosal approach. The tumor was partially removed for diagnosis since it was very hard and tightly attached to the pons. Pathological examinations demonstrated abundant IgG positive plasma cells resting on fibrous tissue. These cells also exhibited positive expression for IgG4, and we therefore diagnosed IgG4-related hypertrophic pachymeningitis. Since the major part of the tumor remained, the prednisolone administration was initiated at 60 mg/day and completed by tapering every 14 days after reaching 1,000 mg methylprednisolone over 3 days. The mass lesion completely disappeared and the bilateral abducens nerve palsies were particularly improved after this treatment. Even though we terminated the glucocorticoid treatment, recurrence has not been recognized for 36 months. The effectiveness of glucocorticoid treatment for IgG4-related hypertrophic pachymeningitis has been described in a few case reports, and a favorable outcome was obtained by us with remarkable shrinkage of a mass lesion and improvement of palsies of the bilateral abducens nerves following glucocorticoid treatment. It is important to perform surgery for the purposes of diagnosis, when IgG4-related hypertrophic pachymeningitis is suspected for a skull base mass, since it can show a good reaction to glucocorticoid treatment.

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