Polyarteritis nodosa - Challenges and options in management

Polyarteritis nodosa (PAN) was one of the first systemic necrotizing vasculitides to be described, in the late 19th century. Hepatitis B virus (HBV) was the major cause of the observed PAN cases between 1970 and the early 2000s. However, in the revised 2012 Chapel Hill Consensus Conference nomenclature, HBV-related PAN is now included with vasculitides associated with probable etiologies (and named HBV-associated vasculitis). PAN should thus now refer exclusively to primary cases, without an identified or probable cause. Besides systemic forms of the primary and “classical” PAN, which have become more rare over the past decade, isolated and/or single organs can be affected, including the skin. In this article, we review the main clinical, biological, and radiological characteristics of “classical” primary PAN and its different forms, their treatment options, and outcomes. We also discuss other possible etiologies (other than HBV) of PAN-like medium-sized vessel vasculitis and newly described PAN-like vasculopathies, such as recessive loss-of-function mutations in adenosine deaminase 2, as well as the treatment options for isolated or refractory cases and the current place of biologic agents for the treatment of PAN.