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. 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 become dilated.
Urticaria and angioedema are typically allergic reactions. When a stimulus to which an individual is allergic to enters the bloodstream, the mast cells that are present in the skin bind to immunoglobulins. The mast cells are then activated and undergo degranulation, resulting in the secretion of inflammatory substances, such as histamine. This induces allergic reaction as well as urticaria and angioedema.
The classification of urticaria and angioedema is based on duration. If the symptoms last for less than 6 weeks, it is classified as acute; anything longer is classified as chronic. These conditions are generally self-limiting, and, when confined to small areas of the skin, do not usually require hospitalization or consultation with a doctor. These lesions can affect any age group, but are more commonly encountered in individuals in their 30s.
Cause of Condition
Urticaria and angioedema can be induced by a number of environmental stimuli. An allergic reaction from intake of seafood, particularly shellfish, chocolates, peanuts and milk products is a relatively common cause. Other causes are 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 cholinergic urticarial, which is believed to be due to a higher body temperature, can be induced by fever, exercise, or a hot bath. Patients with this condition appear flushed because of large areas that become erythematous.
There are other less common physical causes of urticaria and angioedema. Dermatographism is a special kind of urticaria that occurs in approximately 1-4% of individuals. The skin develops a lesion when it is stroked firmly with an object, such as a fingernail. Prolonged pressure, such as in areas where tight clothing or straps are worn, can also result in urticaria. Other causes include exposure to sunlight (solar urticaria), contact with water (aquagenic urticaria), and interaction with chemicals (contact urticaria) and insect venoms. Some medications, specifically NSAIDs and ACE inhibitors, have likewise been reported to result in this condition.
Chronic urticaria is usually idiopathic, which means that there is no known cause for the condition. Some studies have shown an association between the chronic form of the disease and autoimmune thyroid conditions, such as Hashimoto’s thyroiditis. A rare disease known as C1 inhibitor deficiency is a hereditary condition that can result in angioedema without urticaria.
Urticarial lesions are wheals that have an elevated, erythematous border. The lesion is well circumscribed, with a whitish central area. They are typically pruritic or itchy. These lesions can involve any part of the body but commonly occur on the face and the extremities. The lesions can last anywhere from a couple of hours to over a day.
Angioedema, on the other hand, is usually confined to the area around the eyes and on the lips. Since the affected layers in angioedema are deeper, the skin may appear relatively normal, although the area is swollen. It is typically painful. Angioedema can also occur in other areas of the body, specifically the bowels and the respiratory tract. When there is involvement of the gastrointestinal tract, the patient can present with abdominal pain and vomiting. When there is involvement of the respiratory tract, it can involve the larynx, resulting in obstruction and difficulty of breathing.
More severe symptoms of allergic or anaphylactic reactions can accompany urticaria and angioedema. These are systemic symptoms and include wheezing and even hypotension.
Who to See and Types of Treatments Available
One of the most important aspects of the management of urticaria and angioedema is the identification of the allergen causing the condition. An allergologist is a specialist who can diagnose and manage these conditions. A thorough history and physical examination need to be done to determine the causative agents and prevent the condition from recurring. If the allergens cannot be identified, skin testing may have to be performed to determine what the individual is allergic to. Patients are then instructed to avoid intake of or contact with these allergens.
Acute episodes of urticaria and angioedema may be managed with antihistamines, such as loratadine or cetirizine. Both the urticaria and the pruritus are usually addressed by these medications. Patients who do not respond to antihistamines may be given corticosteroids. Patients with pressure urticaria and idiopathic angioedema may be given systemic steroids, as well. Patients with vasculitic urticaria may be prescribed additional medications, such as colchicine or hydroxychloroquine.
Patients with chronic urticaria may be treated with systemic corticosteroids. Leukotriene receptor antagonists, for example montelukast, may also be added to the regimen. Newer drugs, such as omalizumab, may also be given. Those who do not respond to these medications may have to be given stronger drugs, typically immunosuppressants such as cyclosporine. However, these medications are typically considered as last line treatment because of their unwanted side effects.
For more severe anaphylactic reactions, patients are given an injection of epinephrine. If a patient comes in with associated difficulty in breathing, respiratory support with intubation and mechanical ventilation may have to be instituted.
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