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URTICARIA AND ANGIOEDEMA ICD-10: L50
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Urticaria is composed of wheals (transient edematous papules and plaques, usually pruritic and caused by edema of the papillary body) (Fig. 14-1; also see Fig. 14-2). The wheals are superficial and well defined.
Angioedema is a larger edematous area that involves the dermis and subcutaneous tissue (Fig. 14-3) and is deep and ill defined. Urticaria and angioedema are thus the same edematous process but involve different levels of the cutaneous vascular plexus: papillary and deep.
Urticaria and/or angioedema may be acute recurrent or chronic recurrent.
Different forms of urticaria/angioedema are recognized: IgE and IgE receptor dependent, physical, contact, mast cell degranulation related, and idiopathic.
In addition, angioedema/urticaria can be mediated by bradykinin, the complement system, and other effector mechanisms.
Urticarial vasculitis is a special form of cutaneous necrotizing venulitis (see Clinical Manifestation/Phases).
There are some syndromes with angioedema in which urticarial wheals are rarely present (e.g., hereditary angioedema).
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EPIDEMIOLOGY AND ETIOLOGY
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INCIDENCE Fifteen to 23% of the population may have had this condition during their lifetime.
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ETIOLOGY Urticaria/angioedema is not a disease but a cutaneous reaction pattern. For classification and etiology, see Table 14-1.
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ACUTE URTICARIA Acute onset and recurring over <30 days. Usually large wheals are often associated with angioedema (Figs. ...