Recurrent spinal IgG4-related hypertrophic pachymeningitis and its management: a case report

In this report, we share a case of recurrent spinal immunoglobulin G4 (IgG4)-related hypertrophic pachymeningitis (IgG4-RHP) in a patient who initially achieved near-complete recovery of muscle weakness after decompression surgery and steroid therapy. However, the patient experienced disease recurrence after discontinuing steroid therapy due to intolerable side effects.

We reviewed the patient's medical records, including the pathology images and report certified by the pathologist. After disease recurrence, the patient was treated with oral prednisolone 5 mg twice daily and oral azathioprine 50 mg daily initially, which was then increased to 75 mg daily a month later.

After 6 months of combined therapy with prednisolone and azathioprine, there was significant improvement in the patient's clinical symptoms. Interval MRI scans showed resolution of the lesion, and the serum IgG4 concentration also returned to the normal range.

Although the pachymeninges (dura mater) are rarely involved in IgG4-related disease, it should be considered in the differential diagnosis of long-segment, homogeneously enhanced epidural masses. Steroid therapy is the first-line therapy for IgG4-RHP, while steroid-sparing agents should be added in refractory or recurrent cases. Surgical decompression is necessary in cases of acute neurological deterioration. A combination of a steroid and an immunomodulatory agent may be considered in cases of recurrent disease. More importantly, we demonstrated details of the clinical course of IgG4-RHP and the treatment effects of both surgical decompression of the spinal cord and medical treatment with steroids in combination with an immunomodulator (azathioprine), particularly in the setting of disease recurrence. This was done in full detail with interval imaging scans showing the response to treatment, along with serial tracking of the antibody levels, which, to our knowledge, had not been reported prior.