Roadmap to vasculitis: a rheumatological treasure hunt: Part II. Classification, features of individual vasculitides and differential diagnosis against pseudovasculitis

Since the triggering factors causing primary vasculitides are by definition not (yet) known, we have to classify them to clinical syndromes based on the size, site, type and effect of the blood vessel involvement. ACR classification criteria and Chapel Hill nomenclature are useful tools to familiarize with the primary vasculitides, although a lot of criticism has been voiced in the literature indicating that they only represent the best available consensus. The present text takes advantage of the recent developments such as introduction of the anti-neutrophilic cytoplasmic auto (ANCA) antibodies, and divides the vasculitides to those affecting typically the large, medium and small arteries or only small blood vessels. In addition, some vasculitides, which are still difficult to place to the vasculitis map, like Bürger's disease, Goodpasture's syndrome, primary angiitin of the central nervous system (PACNS) and panniculitis, are dealt with. As it is a long and winding road, attention has to be paid to the clinical details to follow the road sign to “pseudovasculitis”, when that is the right way to go. They represent a bunch of non-vasculitic conditions, which lead to structural or vasospastic impairment of the blood flow, bleeding or thromboembolism and hyperviscosity. These imitators have to some extent, similar clinical symptoms and signs as well as laboratory and radiological findings to those found in true systemic vasculitides. This also emphasizes the importance of internal medicine as the intellectual (albeit not necessarily organizational) home of rheumatology and rheumatologists as we deal with conditions like atherosclerosis, antiphospholipid antibody syndrome, infectious endocarditic, myxoma of the heart and cholesterol embolism.