Leukocytoclastic vasculitis

Vasculitis can be caused by circulating immune complexes (due to any antigens, such as drug or infectious agent)  which activate a mechanism of the small vessel`s wall endothelium injury. Histologic chages include fibrinoid necrosis of small blood vessels walls and infiltration of leukocytes with fragmentation of nuclei (leukocytoclastic vasculitis with karyoorrhexis or leukocytoclasia)