Small‐vessel and medium‐vessel vasculitis

Introduction The vasculitides include a broad spectrum of disorders that span a clinical spectrum from benign, self-limited disease to fulminant conditions that are fatal in the absence of therapy. Whereas the large-vessel vasculitides consist of 2 principal disorders, giant cell arteritis and Takayasu arteritis, the mediumand small-vessel vasculitides are much more diverse, including multiple diseases that can affect nearly every organ system. This article is the second of a 2-part series that focuses on the challenges faced by clinicians who care for patients with vasculitis. The first article in this series discussed the large-vessel vasculitides (1). The present article will examine the mediumand small-vessel vasculitides, reviewing the recent literature for insights regarding their epidemiology, pathogenesis, and treatment.