Allergic vasculitis

Allergic vasculitis, also known as hypersensitivity vasculitis, is an allergic reaction caused by drugs or infections. It primarily affects small blood vessels in the skin (arterioles, venules, and capillaries), but can also involve small blood vessels in other organs, leading to multi-system disease. The main manifestations of this disease are palpable purpura and/or petechiae (subcutaneous hemorrhagic spots less than 2 mm in diameter) and ecchymoses (subcutaneous hemorrhagic spots greater than 5 mm in diameter) on the skin. It may be accompanied by symptoms in other systems, including the kidneys, joints, intestines, heart, respiratory system, and nervous system.