AB0707 Four distinct clinical phenotypes of vasculitis affecting medium-sized arteries

Background Polyarteritis nodosa (PAN) is a necrotizing arteritis of medium-sized arteries. PAN is divided into systemic and cutaneous PAN (cPAN). cPAN is further classified into mild cPAN or severe cPAN, which presents with ulcer, necrosis, or neuritis. However, it is sometimes difficult to distinguish between severe cPAN and systemic PAN, and their optimal managements are still unclear. The aim of this study is to evaluate clinical characteristics of patients with necrotizing arteritis of medium and small artery. Objectives To evaluate the clinical characteristics of patients with necrotizing arteritis of medium-sized arteries in order to further clarify the subtypes of PAN. Methods Forty-nine patients diagnosed with necrotizing arteritis of medium-sized arteries between 2008 and 2017 at our institution were enrolled to this study. Patients with evidence of glomerulonephritis or vasculitis in arterioles, capillaries, or venules, which are hallmarks of small-vessel vasculitis, were excluded. Clinical backgrounds, laboratory findings including inflammatory markers and antineutrophil cytoplasmic antibodies (ANCA), affected organs, treatments, and rates of relapse and death were evaluated. Results Among 49 patients, 11 patients (22%) presented with systemic vasculitis. Organ involvement was diverse and ranged from central nervous system to cutaneous manifestations. The remaining 38 patients were diagnosed as cPAN and further classified as mild cPAN (16 patients) or severe cPAN (22 patients: ulcer type, 9; neuritis type, 9; both, 4). There was one case of cPAN which resulted in renal damage. The clinical characteristics of mild cPAN included female predominance (87.5%) and younger age (median, 32), and patients tend to have normal inflammatory markers and laboratory findings. Those of systemic PAN included older age (median, 69), higher levels of inflammatory markers, lower levels of serum proteins, and organ damage. Nonspecific elevation of autoantibodies is frequently observed. Particulary, 54.5% of systemic type possessed MPO-ANCA though the titers were significantly lower than those of microscopic polyangiitis, suggesting non-specific elevation of MPO-ANCA in Japanese population. Severe cPAN manifested with intermediate phenotypes, and inflammatory activities were significantly correlated with age (p<0.001). Although the mortality rates were indistinguishable, the relapse rates of cPAN (ulcer type) were significantly higher than those of other types (88.9%, Figure). The mean doses of prednisolone (PSL) used to treat mild cPAN, severe cPAN, and systemic type were 18.5, 38.6, and 39.1 mg/day, respectively. Immunosuppressants were used in 20% of mild cPAN, 90.9% of severe cPAN, and 72.7% of systemic PAN patients. Most patients with cPAN (ulcer type) were initially treated by corticosteroid monotherapy, and immunosuppressive agents were added when they relapsed. Considering its high relapse rate, it might be reasonable to select combination therapy with cyclophosphamide for severe cPAN (ulcer type) as is proposed in nonsystemic vasculitic neuropathy.Abstract AB0707 – Figure 1 Conclusions The clinical characteristics of mild cPAN, severe cPAN (ulcer type), severe cPAN (neuritis type), and systemic PAN were distinct from each other. Particularly, patients with severe cPAN (ulcer type) had higher relapse rates, thus indicating the importance of combination therapy in this patient cohort. Disclosure of Interest None declared