Key Clinical Updates in Reactive Erythemas
Ligelizumab is effective for chronic urticaria in early clinical trials.
Etanercept is emerging as a promising therapy for Stevens-Johnson syndrome/toxic epidermal necrolysis and is now the treatment of choice in some centers.
1. URTICARIA & ANGIOEDEMA
ESSENTIALS OF DIAGNOSIS
Evanescent wheals or hives.
Intense itching; rarely, pruritus may be absent.
Most episodes are acute and self-limited (1–2 weeks).
Urticaria is divided into acute and chronic forms.
Chronic urticaria (episodes lasting longer than 6 weeks) may have an autoimmune basis.
Urticaria may be acute (less than 6 weeks’ duration) or chronic (more than 6 weeks’ duration). Urticaria can result from many different stimuli on an immunologic or nonimmunologic basis. The most common immunologic mechanism is mediated by IgE, as seen in the majority of patients with acute urticaria; another involves activation of the complement cascade. Some patients with chronic urticaria demonstrate autoantibodies directed against mast cell IgE receptors. ACE inhibitor and angiotensin receptor blocker therapy may be complicated by urticaria or angioedema. Cholinergic urticaria is triggered by a rise in core body temperature (hot showers, exercise). Cold urticaria is acquired or inherited and triggered by exposure to cold and wind (see Chapter 37). In general, extensive costly workups are not indicated in patients who have urticaria. A careful history and physical examination are more helpful. Chronic urticaria that has no identifiable trigger is termed chronic spontaneous urticaria. Chronic urticaria that is reproducibly triggered by specific exposures is called chronic inducible urticaria. Examples include cholinergic urticaria, solar urticarias, cold urticaria, dermatographism, and delayed pressure urticaria. Autoimmune thyroid disease may be associated with autoimmune urticaria, and acute hepatitis infection may be associated with urticarial vasculitis.
Lesions are itchy, red swellings of a few millimeters to many centimeters (Figure 6–23). The morphology of the lesions may vary over a period of minutes to hours, resulting in geographic or bizarre patterns (eFigure 6–63). Individual lesions in true urticaria last less than 24 hours, and often only 2–4 hours. Angioedema is involvement of deeper subcutaneous tissue with swelling of the lips, eyelids, palms, soles, and genitalia. Angioedema is no more likely than urticaria to be associated with systemic complications, such as laryngeal edema or hypotension. Dermatographism is induced by scratching and can be elicited during the clinic visit by scratching the patient’s skin. The wheals of cholinergic urticaria are 2–3 mm in diameter with a large surrounding red flare.
Urticaria (hives). (Reproduced, with permission, from Bondi EE, Jegasothy BV, Lazarus GS [editors]. Dermatology: Diagnosis & Treatment. Originally published by Appleton & Lange. Copyright © 1991 by The McGraw-Hill Companies, Inc.)
Urticaria. (Used, with permission, from TG Berger, ...