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

Objective: Within the spectrum of polyarteritis nodosa (PAN), cutaneous PAN (cPAN) is further classified into mild cPAN and severe cPAN which presents with ulcers, necrosis, or neuritis. As distinguishing between severe cPAN and systemic PAN can be difficult, this study evaluated the clinical characteristics of patients with necrotizing arteritis of medium-sized arteries. Methods: Forty-one patients diagnosed with necrotizing arteritis of medium-sized arteries between 2008 and 2017 at our institution were enrolled in this study. Clinical background, laboratory findings, treatments, and rates of relapse and death were evaluated. Results: Thirty-six patients were classified as having cPAN (mild, 15; ulcer, nine; neuritis, eight; both, four), and five cases manifested systemic vasculitis. Clinical characteristics of mild cPAN included female predominance (84.6%) and younger age (median 31 years); those of systemic PAN included older age (median 71 years) and higher levels of inflammatory markers. Severe cPAN manifested with intermediate phenotypes. The median doses of prednisolone used to treat mild cPAN, severe cPAN, and systemic PAN were 20.0, 40.0, and 40.0 mg/day, respectively. Immunosuppressants were used in 20.0% of mild cPAN, 90.5% of severe cPAN, and 80.0% of systemic PAN patients. Although the mortality rates were indistinguishable, the relapse rates of severe cPAN (ulcer type) were significantly higher than those of other types (88.9%). Conclusion: The clinical characteristics of mild cPAN, severe cPAN (ulcer type), severe cPAN (neuritis type), and systemic PAN were distinct from each other. In particular, patients with severe cPAN (ulcer type) had higher relapse rates, indicating the importance of combination therapy.