Clinical characteristics of patients with polyarteritis nodosa based on a nationwide database in Japan

Re-emphasising the importance of catheter-based angiography to differentiate polyarteritis nodosa from cutaneous arteritis: Two case reports

Polyarteritis nodosa (PAN) is a systemic necrotising vasculitis with a poor prognosis, characterised by inflammation and necrosis of medium-sized arteries. PAN patients can present with a wide range of systemic manifestations, whereas cutaneous arteritis (CA) is a restricted manifestation to skin of the disease with a more favourable prognosis. Thus, differentiation between PAN and CA is crucial. Here, we present two cases that were initially diagnosed as CA due to the limited presence of systemic symptoms, but were finally diagnosed as PAN through catheter-based angiography. Although contrast-enhanced computed tomography and computed tomographic angiography are increasingly used to diagnose PAN, neither case had any abnormal findings on these examinations. Our cases therefore underscore that catheter-based angiography is critical for differentiation between PAN and CA, even in cases with limited systemic symptoms.

Classification and epidemiology of vasculitis: Emerging concepts

The recent publication of the American College of Rheumatology (ACR)-European Alliance of Associations for Rheumatology (EULAR) classification criteria for large vessel vasculitis and anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAVs) has provided modern criteria for the classification of these conditions, which incorporate contemporary methods of investigation and diagnosis. Further validation is required in independent cohorts, especially from populations that were not well represented in the development cohort. Studies of the occurrence of large vessel vasculitis report that Takayasu arteritis is a rare disease in most populations, and giant cell arteritis is the most common vasculitis in older populations. The incidence of AAV appears to have plateaued, but the prevalence is increasing as a result of lower mortality. The new classification criteria may affect the reported incidence and prevalence, and studies will be needed to confirm this. The impact of COVID-19 on the occurrence of the vasculitides is not completely known, but there is evidence of reduced occurrence of Kawasaki disease and IgA-associated vasculitis following lockdowns with reduced transmission of possible trigger infectious agents.