Neurosurgical and neuro-immunological management of IgG4-related hypertrophic sclerosing pachymeningitis. A literature survey and discussion of a unique index case

Background: Dural thickening is observed in lymphoma, dural carcinomatosis, meningioma, tuberculosis, and autoimmune diseases. We encountered a patient with dural thickening and complaints of neck and back pain, numbness and loss of strength in the hands. The patient also suffered from polychondritis and had previously received steroid and methotrexate treatment for this indication. The patients' serum was also positive for ANA, yet she did not have any other findings suggesting lupus. Our radiological and pathological analysis revealed IHSP (IgG4-related hypertrophic sclerosing pachymeningitis). In this review study, we provided a detailed literature survey to increase the awareness about IHSP in the neurosurgical community. Methods: MRI (magnetic resonance imaging)-based radiological analyses revealed a posterior extramedullary spinal mass extending from C2 to T2-T3 level. The dural mass was surgically excised and a broad panel of immunohistochemical markers including S100, EMA, CD246/ALK-1, CD45, CD20, CD79a, CD138, CD68, CD1a and CD34 was studied. Immunoglobulin heavy chain/kappa chain gene rearrangement analysis was performed which ruled out a lymphoproliferative disorder. Results: MRI and pathological findings suggested IHSP. As the disease relapsed with a new anterior extra-medullary multilobulated lesion extending from C5 to T1 level, the patient is now closely monitored for further medical and surgical treatment. Conclusions: IHSP is a relatively novel entity of hypertrophic pachymeningitis and should be included in the differential diagnosis of dural thickening. The fibrosis accompanying IHSP may not respond to medical treatment, which includes steroids and immunosuppressive agents. Additionally, neurological deficits, seizures, spinal decompression, hydrocephalus, or brainstem compression necessitate early surgical intervention. A continued vigilance is also necessary as the disease may relapse long-term following surgical treatment.