[The changing face of medium-sized vasculitis].

Polyarteritis nodosa is a systemic necrotizing vasculitis which predominantly affects medium-sized arteries. It is a rare disease nowadays. Both the nomenclature and the classification of polyarteritis nodosa was amended several times in the past. Currently, there is a distinction between the primary form described as classical polyarteritis nodosa and other forms that are associated with their probable cause e.g. with viral hepatitis B, C or HIV infection. Moreover, polyarteritis-like necrotizing vasculitis can appear in the course of genetic diseases caused by mutations in single genes. The pathogenesis of idiopathic polyarteritis nodosa is still unclear, but a dominant role of the adaptive immune system disorders is suggested. Interestingly, in the hepatitis B virus-related vasculitis development, immune complexes are believed to play a crucial role. The spectrum of clinical manifestations of polyarteritis nodosa is wide, from involving a single organ to the polyvisceral failure. In the course of polyarteritis nodosa nearly each organ can be involved, however the disease never affects the lungs. Special forms of polyarteritis nodosa include a single-organ disease and a cutaneous form. The diagnosis of polyarteritis nodosa requires integration of clinical, angiographic and biopsy findings. Recognizing the form of polyarteritis nodosa, determining affected organs and the progression of the disease is very important since those are deciding factors when choosing treatment strategies.