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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).

Figure 14-1

Acute urticaria Small and large wheals with erythematous borders and a lighter color centrally. Well defined. The lesion on the left upper arm is ill defined at its lower border where it is regressing.

Figure 14-2

Chronic urticaria Chronic urticaria of 5-year duration in an otherwise healthy 35-year-old female. Eruptions occur on an almost daily basis and, as they are highly pruritic, greatly impair the patient's quality of life. Although suppressed by antihistamines, there is an immediate recurrence after treatment is stopped. Repeated laboratory and clinical examinations have not revealed an apparent cause. This condition is therefore called chronic idiopathic urticaria.

Figure 14-3

Acute urticaria and angioedema Note that there are both superficial wheals and deep, diffuse edema. Occurred after the patient had eaten shellfish. He had similar episodes previously but never considered seafood as the cause.


INCIDENCE Fifteen to 23% of the population may have had this condition during their lifetime.

ETIOLOGY Urticaria/angioedema is not a disease but a cutaneous reaction pattern. For classification and etiology, see Table 14-1.

TABLE 14-1Etiology and Classification of Urticaria/Angioedema


ACUTE URTICARIA Acute onset and recurring over <30 days. Usually large wheals are often associated with angioedema (Figs. ...

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