Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Hypersensitivity vasculitis ?
    ### Response:
    Hypersensitivity vasculitis is an extreme reaction to a drug, infection, or foreign substance that leads to inflammation and damage to blood vessels of the skin. Signs and symptoms may include purple-colored spots and patches on the skin; skin lesions on the legs, buttocks, or trunk; blisters on the skin; hives (urticaria); and/or open sores with dead tissue (necrotic ulcers).
    