Akademik

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An eruption of itching wheals, usually of systemic origin; it may be due to a state of hypersensitivity to foods or drugs, foci of infection, physical agents (heat, cold, light, friction), or psychic stimuli. SYN: hives (1), urtication (2). [L. urtica]

- acute u. SYN: febrile u..

- u. bullosa an eruption of wheals capped with subepidermal vesicles. SYN: u. vesiculosa.

- cholinergic u. a form of physical or nonallergic u. initiated by heat ( e.g., hot baths, physical exercise, pyrexia, exposure to sun or to a warm room) or by excitement; the rather distinctive lesions consist of pruritic areas 1–2 mm in diameter surrounded by bright red macules. SYN: heat u..

- chronic u. a form of u. in which the wheals recur frequently, or persist. SYN: u. chronica.

- u. chronica SYN: chronic u..

- cold u. wheal formation that develops after exposure to lowered temperatures, with or without demonstrable passive-transfer antibodies.

- u. endemica, u. epidemica u. caused by the nettling hairs of certain caterpillars.

- factitious u. SYN: dermatographism.

- febrile u. u. accompanied by mild fever. SYN: acute u..

- giant u. SYN: angioedema.

- heat u. SYN: cholinergic u..

- u. hemorrhagica u. bullosa in which the serous exudate contains blood.

- u. maculosa a chronic form of u. with lesions of a red color and little edema.

- u. medicamentosa an urticarial form of drug eruption.

- papular u. a sensitivity reaction to insect bites, especially human and pet fleas, seen mostly in young children as wheals followed by papules on exposed areas.

- u. perstans a form of chronic u. in which the wheals persist unchanged for long periods; includes urticarial vasculitis.

- u. pigmentosa cutaneous mastocytosis resulting from an excess of mast cells in the superficial dermis, producing a chronic eruption characterized by flat or slightly elevated brownish papules which urticate when stroked. The disease in children frequently involutes spontaneously whereas resolution is rare with adult onset and there may be systemic lesions. SEE ALSO: diffuse cutaneous mastocytosis.

- pressure u. u. of unknown etiology occurring after local pressure on the skin.

- solar u. a form of u. resulting from exposure to sunlight; some patients have passive-transfer antibodies and others do not.

- u. subcutanea u. in which itching is present without the wheals.

- u. vesiculosa SYN: u. bullosa.

- vibratory u. a form of u. that occurs in response to vibratory stimuli.

ur·ti·car·ia .ərt-ə-'kar-ē-ə, -'ker- n HIVES

ur·ti·car·i·al -ē-əl adj

an itchy rash resulting from the release of histamine by mast cell. Individual swellings (weals) appear rapidly and resolve spontaneously within hours. Acute urticaria is common and represents an immediate response to such allergens as seafood or strawberries. Chronic urticaria is not an allergic condition and may persist for years. Angio-oedema occurs when the weals involve the lips, eyes, or tongue, which may swell alarmingly and constitute a medical emergency. Urticaria can be prevented by taking antihistamines regularly. Cholinergic urticaria is a condition in which very small weals are brought on by heat, exercise, or emotion; treatment may be with hydroxyzine or ketotifen.