Granulomatous dural infiltrate with vasculitis, giant cells, and elevated c-ANCA titers; consistent with Wegener's granulomatosis involving dura of cervical spinal cord.
DISCUSSION: Wegener's granulomatosis is a rare inflammatory disorder of unknown etiology characterized by acute necrotizing granulomas of the upper and lower respiratory tract, with or without systemic vasculitis and focal or diffuse necrotizing glomerulitis (3,6). Localized forms of Wegener's granulomatosis lacking the complete clinical triad are increasingly recognized. Neurologic involvement, usually in the form of peripheral or cranial neuropathy, is common (22% to 54% of cases), but appears to have decreased as a result of effective therapeutic agents (4). Involvement of the brain and meninges is infrequent, but occurs in 2% to 8% of cases (3,6,8).
Meningeal involvement in Wegener's granulomatosis may develop during the disease course (4,10) or be the initial clinical manifestation (9,11,12). The involved meninges are typically thickened and abnormal enhancement is demonstrable on imaging studies. Nodular meningeal involvement, producing a mass, has been reported within the cranial cavity (9,11). This case of dural involvement by Wegener's granulomatosis forming an encircling mass of the cervical cord appears to be unique in the English literature. The case is also remarkable for the need for surgical decompression. While at the time the patient presented with her dural mass there was no other clinical evidence of systemic disease, the clinical history of mastoiditis in retrospect may be suspicious for upper respiratory involvement. Primary otologic Wegener's granulomatosis presenting as acute mastoiditis has been previously described (1,5). Unfortunately, tissue from our patient's previous mastoidectomy was unavailable for review.
The diagnosis in this case is strongly supported by the histologic features of granulomatous inflammation and vasculitis in the resected tissue mass, coupled with the finding of positive cytoplasmic antineutrophil cytoplasmic antibodies (c-ANCA). The specificity of c-ANCA, as measured by ELISA, for Wegener's granulomatosis is reportedly 98% (7). Other vasculidites such as polyarteritis nodosa may also be positive for c-ANCA, but usually in lower titer. The sensitivity of c-ANCA, as measured by ELISA, for Wegener's granulomatosis correlates with disease activity and extent. Sensitivity is reported as 93% for active generalized disease, 60% for active localized disease and 40% for patients in remission (7).
Many untreated patients with generalized Wegener's granulomatosis experience a rapidly progressive, fatal illness (3). Corticosteroids and daily oral cyclophosphamide have been the mainstay of effective therapy. The standard and proposed alternative approaches to treatment of Wegener's granulomatosis have recently been reviewed (2). Meningeal disease in Wegener's granulomatosis has been reversed with both oral (12) and intrathecal (10) immunosuppressive regimens. In the latter case, disease resolution correlated with negative CSF c-ANCA titers. In another case, meningeal involvement developed despite intravenous cyclophosphamide and oral prednisone therapy, necessitating an increased dose of both agents prior to disease resolution (4). In the present case, dramatic neurologic improvement followed surgical decompression and treatment with corticosteroid therapy.
Contributed by Paul J McCarthy, MD, William P Arend, MD, B K Kleinschmidt-DeMasters, MD