[Para-infectious vasculitis]

Vasculitis is histologically characterized by inflammatory infiltrates of the vessels. In case of secondary vasculitis, the etiology is known. It may be an infection, a neoplasia, drugs or an autoimmune disease. In contrast, in primary vasculitis, no triggering event can be detected. In case of vasculitis associated to infection, the skin lesion may be the clue for the underlying infection. In case of endocarditis (Osler node, Janeway lesion) or sepsis due to Pseudomonas aeruginosa (ecthyma gangrenosum), the skin lesions are quite specific for the underlying disease. Other skin lesions are just an unspecific reaction to a microbial stimulus. Five clinical examples of vasculitis associated to infection, and an important non-infectious differential diagnosis are presented. The cases underline that a broad general work-up with multiple serological tests is neither cost-effective nor diagnostically rewardable. In contrast, if vasculitis is suspected to be caused by infection, the individual work-up should be based on the case-history, the epidemiology and the clinical presentation.