Vasculitis displays classic histological findings of predominantly neutrophilic infiltrates affecting small and medium-sized blood vessels. Large vessel vasculitis occurs in some cases. Fibrinoid deposits, endothelial edema, and extravasation of red blood cells are common. A mixed inflammatory infiltrate occurs, particularly in subacute stages older lesions. The functional and phenotypic heterogeneity of the vascular endothelial lining, which is the primary target of injury, dictates different types of vascular lesions in the various organs, variability in clinical presentation, prognosis and therapy [85].