Urticaria

Urticaria is a disease of allergic and toxic genesis characterized by urticarial eruptions on the skin and less frequently on the mucous membranes. The transudation of fluid from small cutaneous blood vessels results in urticarial lesions. Mast cells play a primary role in this process. Mast cell granules contain histamine, chemotactic factors for eosinophils and neutrophils, prostaglandins, platelet-activating factor, and leukotrienes. All these products are released when a mast cell is stimulated. Histamine therefore is an important factor in the pathogenesis of urticaria. The type 1 IgE-mediated hypersensitivity state is a common immunologic mechanism involved in urticaria. Allergens involved in type 1 reactions may include medications and foods or result from infections and insect bites. Type III serumsickness-like reactions sometimes are responsible for eliciting urticaria by activating the complement system. A large number of medications, including morphine, codeine, meperidine, quinine, aspirin, nonsteroidal anti-inflammatory agents, and radiocontrast media, directly stimulate histamine release. Specific physical promoters, including cold, heat, vibration, and light, result in histamine and other mediator release in predisposed individuals. Exogenic (physical, thermal, mechanical, chemical agents, drugs, antibiotics in particular, sera and foods) and endogenic (pathological processes in the viscera, e.g. gastro-intestinal tract, liver, disturbed activity of the nervous system) causes of urticaria are distinguished. The pathogenic mechanism of its development in all cases has many links in common. The etiological (autogenic and exogenic) factors promote the development of immediate-delayed hypersensitivity and thus cause the accumulation of chemically active substances of the type of histamine. Histamine induces dilation of the capillaries and increases the permeability of the vascular walls, as a consequence of which acute oedema of the dermal papillary layer develops and causes the appearance of blisters on the skin.

In particular, cholinergic urticaria developing in nervous excitation is caused by the production of acetylcholine in the tissues under the effect of irritation of the cholinergic (parasympathetic) system. Acetylcholine induces a vascular reaction similar to the reaction to histamine. Autosensitization to acetylcholine with the development of an auto-antigen-auto-antibody reaction may also occur. In bites of bloodsucking insects (mosquitoes, fleas, midges, mits) chemically active agents of the type of histamine enter the skin with their saliva. Invasion by helminths plays a tremendous role in the development of urticaria.

The clinical picture of urticaria has a great variety, in view of which several types are distinguished: acute, including Quincke's acute circumscribed oedema (angioneurotic oedema), chronic recurrent and stable chronic papular urticaria.

Acute urticaria is characterized by an abrupt onset: the appearance of severe itching and abundant urticarial lesions of various size elevated above the skin surface. They are pinkish-red with a mat hue in the centre and a pink fringe with uneven contours on the periphery. The wheals are usually round, less frequently elongated and irregular in shape. The lesions may coalesce into extensive zones and the general condition of the body may be disturbed (elevated body temperature, gastro-intestinal disorders, indisposition, chill, i.e. ‘urticarial fever’). The wheals are mainly localized on the trunk, hands, buttocks and less frequently on other skin areas. Eruptions may occur on the mucous membranes of the lips, tongue, soft palate, nasopharynx and larynx, in which event the oedema makes respiration and swallowing difficult. The wheal eruptions are ephemeral, i.e., the lesions are short-lived and usually disappear in one or two hours. Acute urticaria lasts several days. Drug or food allergy (parenteral administration of therapeutic sera, vaccines, transfusion of blood, etc.) is usually encountered. Artificial urticaria is an atypical variety of acute urticaria. It is characterized by the formation of wheals, usually linear, in response to mechanical irritation, i.e. in demonstrating dermatographia. In distinction from common urticaria, there is no itching.

Acute circumscribed oedema (syn. giant urticaria, angioneurotic oedema, Quincke's disease) is characterized by sudden development of circumscribed oedema of the skin (mucous membrane) and subcutaneous fat of the face (lips, cheeks, eyelids, etc.) or the genitals. The skin is hard-elastic to the touch and white or less frequently pink. There are usually no subjective sensations though in rare cases burning and itching may be experienced. The oedema subsides in a few hours or in one or two days, but recurrences are possible. Angioneurotic oedema is sometimes combined with ordinary urticaria. In oedema of the larynx, stenosis and asphyxia may occur. In localization of oedema in the region of the orbits, the eyeballs may be displaced medially and acuity of vision is reduced.

Chronic recurrent urticaria is distinguished by less abundant eruptions, but occurs in attacks for several months-or years and usually develops against the background of long-term sensitization caused by foci of chronic infection (tonsillitis, adnexitis, etc.), disturbed activity of the gastro-intestinal tract, liver, etc. Recurrences of the disease characterized by the appearance of urticaria on different skin areas are replaced by remissions of various duration. Headache, weakness, elevated body temperature and arthralgia may develop during eruption of the urticarial lesions, while nausea, vomiting and diarrhoea may occur in oedema of the gastro-intestinal mucosa. Agonizing itching may be attended with insomnia and neurotic disorders. The blood is marked by eosinophilia and thrombocytopenia.

Stable papular urticaria develops when persistent stable urticarial lesions transform into papules as the result of the development of cellular infiltration (composed mainly of lymphocytes) in the dermis as well as hyperkeratosis and acanthosis, in addition to the stable circumscribed oedema. The papules are reddish-brown and are mostly localized on the extensor surfaces of the limbs. The disease is usually encountered among females. Many authors claim that stable papular urticaria should be considered a variety of prurigo.

Solar urticaria is a variety of photodermatosis which develops in individuals suffering from diseases of the liver and disturbed porphyrin metabolism in marked sensitization to ultra-violet rays. It is mostly encountered among females. The disease is characterized by the appearance of urticarial eruptions on exposed skin areas (face, upper limbs, etc.). It is of seasonal character (spring and summer). In long-term exposure to the sun, the eruptions may be attended with a general body reaction in the form of disorders of respiration and cardiac activity; shock may occur.

Treatment. In acute and chronic urticaria it is essential to identify and remove all possible pathogenic factors contributing to the development of the disease. Special attention should be paid to the diet, regimen, condition of the nervous system and gastro-intestinal tract and detection and treatment of foci of chronic infection. It is highly advisable for the patient to consult a neurologist and otorhinolaryngologist and to examine the patient for helminths and, whenever necessary, carry out dehelminthization, to treat foci of chronic infection and to remove alimentary and drug allergens. A salt purgative, a diet of dairy products and vegetables, sedatives, hypersensitizing agents (calcium preparations, infusion of sodium hyposulphite, injections of magnesium sulphate), and antihistaminics are prescribed. Preparations of bromide and valerian, Peritol, Tavegil, Diazolin, Stugeron (Cinnarizine), Suprastin, Diprazine, Seduksen (Diazepam), as well as drugs containing ephedrine and belladonna and their derivatives are used. To reduce vascular permeability, calcium chloride, calcium gluconate or calcium lactate are prescribed simultaneously orally or intramuscularly together with vitamin C and rutin. Purgatives, cleansing enema, and in some patients diuretics (furosemid, theobromine and sodium salicylate) may prove valuable in acute urticaria. Salicylates, vitamins B₁₂ and B₆, sodium hyposulphite, Salol and Atophan (Cinchophen) are recommended in chronic urticaria for correcting metabolic processes. In severe forms of the disease corticosteroid hormones are given, followed by histaglobin therapy. External therapy is of no essential importance. Aqueous-zinc pastes, ointments with corticosteroid hormones and baths with a decoction of bur-marigold, chamomile, starch or bran are prescribed.

The prognosis is usually favourable. Attention should be focused at identifying and removing the allergenic factors. Regular treatment combined with rational organization of the diet regimen and care may result in clinical recovery.

The prevention of urticaria consists of treatment of gastro-intestinal disorders, diseases of the liver, and foci of infection, removal of the allergenic factors, and prescription of a rational dietary regimen.