ANCA-associated vasculitis manifested by hypertrophic spinal pachymeningitis

63 year old female with endometrial cancer (2012) and myeloperoxidase (MPO) antineutrophil cytoplasmic antibody (ANCA) associated vasculitis diagnosed in 2013. Present with progressive back pain and bilateral distal hand and feet weakness and numbness.

MRI of the thoracic spine from 10/2022 shows long segment ventral dural based enhancing mass demonstrating hypointensity in all other sequences (including T2) extending from T1 to T9 levels (Figure 1A-C; cranial and caudal boarders not visualized due to thoracic levoscoliosis). The mass is predominantly centered in the ventral extramedullary space with some areas of asymmetric left-sided involvement without extension to the neuroforamina (Figure 1D). It measures up to 0.7 cm in maximal thickness at T7-T8 level, and contributes to flattening the ventral cord from T3 through T8 with slight displacement of the cord and effacement of the thecal sac. No cord signal abnormality. CT of the chest does not show areas of mineralization (Figure 1E). Findings are significantly progressed when compared to MRI from 05/2013 (Figure 1F).

We have described a patient with known MPO-ANCA-associated vasculitis since 2012 with sural nerve biopsy demonstrated necrotizing vasculitis involving epineural arteries.  The patient developed hypertrophic spinal pachymeningitis during the course of disease, retrospectively observed already in 2013 with final diagnosis was made in 2022 Her hypertrophic spinal pachymeningitis presented as progressive back pain and bilateral upper and lower neuropathy.

ANCA-associated vasculitis is a complex systemic autoimmune disease characterized by destruction and inflammation of small vessels and tissue necrosis [1]. The disease is divided into three groups according to clinical features: granulomatosis with polyangiitis, microscopic polyangiitis, and eosinophilic granulomatosis with polyangiitis [2]. Vasculitis can occur in any organ or tissue, commonly affecting the respiratory tract and kidneys, and can lead to life-threatening renal failure or pulmonary hemorrhage [3]. Hypertrophic spinal pachymeningitis  is not a common manifestation of ANCA-associated vasculitis. It is an inflammatory disorder causing focal or diffuse thickening of the spinal dura mater. The current standard of care for ANCA vasculitis aimed to achieve remission in the initial phase and then a longer-term maintenance phase [1]. Remission induction involves high-dose glucocorticoids in combination with cyclophosphamide or rituximab. The subsequent maintenance phase usually involves rituximab, methotrexate, azathioprine, or mycophenolate mofetil, sometimes in combination with reduced-dose glucocorticoids. A good symptomatic response to treatment of glucocorticoids, as well as laboratory and radiological findings support the final diagnosis of ANCA-associated vasculitis hypertrophic spinal pachymeningitis. Invasive biopsy of the dura was not performed in this case due to unnecessary risk for the patient.

Current treatments for ANCA vasculitis have a substantial degree of efficacy in inducing and maintaining remission in many patients; however, due to the heterogeneity in presentation of these diseases, diagnosis is often substantially delayed, leading to poor outcomes [4]. Furthermore, treatment adverse effects commonly present [5].

In patients with ANCA-associated vasculitis with suspected hypertrophic spinal pachymeningitis, spinal contrast-enhanced MRI is an established essential modality for potentially facilitate early recognition and intervention to prevent irreversible neurological impairment.  MRI findings of hypertrophic spinal pachymeningitis usually include extramedullary mass extending over multiple vertebral levels, most commonly involving thoracic cord, with signal characteristics of hypointense signal on T2-weighted images, and hypo- or iso-intensity on T1WI with associated enhancement.

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