ABSTRACT
Urticaria are lesions that are edematous with raised round or oval centers, of varying size and may occur anywhere on the body. Urticaria is transient skin lesions that last for minutes to hours and resolve completely within about 24 hours. Angioedema is non-pitting edema that affects deeper tissue layers and is associated with approximately 40% of urticaria cases. The edema occurs in the deep dermis and subcutaneous tissues. The primary clinical manifestation of urticaria is the symptom of pruritus. The major effector cells of urticaria are mast cells, although basophils are also implicated. The causes of acute urticaria include systemic allergic reactions, ingestion of allergens, skin contact with allergens, pseudo-allergic reactions, toxic reactions and viral infections. Hereditary angioedema types I and II are caused by deficient or defective C1 inhibitor, a regulatory protein which is involved in controlling the complement and kinin-generating pathways. Idiopathic angioedema is often a therapeutic dilemma.
