Leukocytoclastic vasculitis (LcV) is the most common form of vasculitis of the skin and usually results from deposition of immune complexes at the vessel wall. It presents in different forms and in association with different diseases.

There are multiple causes of leukocytoclastic vasculitis however in nearly half of all cases the etiology is unknown. An allergic reaction to drugs, food, or food additives supports the theory of the immune system playing the dominant role.