hypersensitivity vasculitis (MONDO_0006794, a Monarch Disease Ontology term) is a small vessel vasculitis affecting the skin and/or internal organs. It is characterized by the presence of neutrophils and fibrinoid necrosis in small arteries and venules. It may be idiopathic or the result of drug treatment, infections, food intake, collagen vascular disorders, inflammatory bowel disease, or cancer. Also known as: leukocytoclastic vasculitis.