Background/Purpose: Systemic sclerosis (SSc) is a complex autoimmune disease characterized by autoantibody production, skin and visceral fibrosis, and vasculopathy. The onset of ANCA-associated vasculitides (AAV) has been anecdotally reported during SSc, but data on the impact of SSc on AAV management and vice-versa, in particular the risk of high doses glucocorticoids, are lacking. The aim of this study was to describe the rare association of SSc and AAV, the management of this complex condition and the impact of treatment on both diseases.

Methods: We conducted a retrospective study in 18 centers in France to include patients presenting both SSc and AAV. All patients met the 2013 ACR/EULAR criteria for SSc and 2022 ACR/EULAR criteria for AAV. Clinical, biological, and radiological data were collected for each patient.

Results: We included 30 patients with the association of SSc and AAV (median age 51.5 years, 83% women). SSc always preceded AAV diagnosis and median time between diagnosis of SSc and AAV was 5 years (0-28). Nine patients (27%) had a diffuse cutaneous form while the others presented a limited cutaneous form. Median modified Rodnan skin score at AAV diagnosis was 5.5 (IQR 4-12). Antibodies against Scl70 were found in half of cases, anti-centromere antibodies in 20%, antinuclear antibodies without any specificity in 20%, and one patient had anti-RNA-polymerase III antibodies. Infiltrative lung disease (ILD) was present in 80% with a computed tomography pattern of non-specific interstitial pneumonia with fibrosis in 54%, non-specific interstitial pneumonia without fibrosis in 13%, usual interstitial pneumonia in 21% and undeterminate pattern in 12%.

AAV type was microscopic polyangiitis in 27 cases (90%), granulomatosis with polyangiitis in 2 cases (7%) and eosinophilic granulomatosis with polyangiitis in one case. ANCA were positive in 29 patients with MPO-ANCA in 28 patients (93%). At AAV diagnosis, renal involvement was present in 76% with a median serum creatinine level of 170 µmol/l (55-572) and proteinuria of 2 g/g (0.7-9), and peripherical neuropathy and cutaneous involvement in 4 cases (13%) each.

All patients received glucocorticoids at a median initial dose of 0.8 mg/kg/day (IQR 0.5-1) and 15 patients (50%) received pulses of methylprednisolone. Induction immunosuppressive regimen was cyclophosphamide in 15 patients, rituximab in 14 patients and only one patient received glucocorticoids only. Vasculitis remission was achieved in 29 cases (97%), and maintenance regimen was initiated in 24 patients and was based on rituximab (n=16), azathioprine (n=6) or mycophenolate mofetil (n=4).

Importantly, no case of scleroderma renal crisis occurred under high dose glucocorticoids used for AAV treatment. SSc remained stable during follow-up, especially skin involvement and ILD.

Conclusion: ANCA-associated vasculitides may occur during SSc, especially in patients with fibrosing ILD, limited cutaneous form and anti Scl70. ANCA-associated vasculitides was mainly microscopic polyangiitis with MPO-ANCA and frequent renal involvement. Vasculitis treatment was based on high glucocorticoids associated with cyclophosphamide and rituximab, and no scleroderma renal crisis was noted.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/onset-of-anca-associated-vasculitides-in-systemic-sclerosis-phenotype-management-and-outcomes/