Hypersensitivity syndromes.
The hypersensitivity syndromes are a group of diseases in which the cutaneous vasculature is altered through immunologic or nonimmunologic mechanisms. These reactions range in severity from mild to life-threatening and can be triggered by drugs, infectious agents, foods, or environmental allergens. Although their causes may vary, the morphologic appearance of these entities may be similar making a clinical diagnosis a challenge.
Adolescent↗