RT Book, Section A1 Wolff, Klaus A1 Johnson, Richard Allen A1 Saavedra, Arturo P. A1 Roh, Ellen K. SR Print(0) ID 1140791122 T1 THE SKIN IN IMMUNE, AUTOIMMUNE, AUTOINFLAMMATORY, AND RHEUMATIC DISORDERS T2 Fitzpatrick's Color Atlas and Synopsis of Clinical Dermatology, 8e YR 2017 FD 2017 PB McGraw-Hill Education PP New York, NY SN 9781259642197 LK accessmedicine.mhmedical.com/content.aspx?aid=1140791122 RD 2024/03/28 AB 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).