Definition and Overview
Urticaria and angioedema are two separate conditions that can occur together. Both are manifestations of edema on the skin.
Urticaria, known in layman’s terms as hives, is an inflammatory reaction that involves the superficial part of the dermis only. Angioedema, on the other hand, involves the deeper skin layers and the subcutaneous tissues. Both conditions are the result of edema; microscopically, the collagen fibers in the skin layers affected become widely separated, and the blood vessels can become dilated and leak.
Urticaria and angioedema are typically allergic reactions. Thus, when a stimulus to which an individual is allergic to enters the bloodstream, specific cells present in the skin, known as mast cells, bind to immunoglobulins. The mast cells are then activated and undergo…show more content… An allergic reaction from intake of seafood, particularly shellfish, chocolates, peanuts and milk products is a relatively common cause of urticaria and angioedema. Another type that is commonly encountered is seasonal urticaria and angioedema, which can occur due to exposure to and inhalation of pollen, mold spores and animal dander.
Cold temperature has been known to induce urticaria. After being exposed to cold temperatures, a patient with this condition develops localized urticaria within a few minutes, as the body is returning to its normal temperature. Although the condition is typically localized, it can become systemic and result in vascular collapse if the entire body is subjected to cold temperatures, such as when swimming in cold water.
On the other extreme is a condition known as cholinergic urticaria. This condition is believed to be due to an increase in body temperature, and can be induced by fever, exercise, or a hot bath. Patients with this condition appear flushed because of large areas that become
