TY - CHAP M1 - Book, Section TI - The Skin in Immune, Autoimmune, Autoinflammatory, and Rheumatic Disorders A1 - Saavedra, Arturo P. A1 - Roh, Ellen K. A1 - Mikailov, Anar PY - 2023 T2 - Fitzpatrick’s Color Atlas and Synopsis of Clinical Dermatology, 9e AB - Urticaria is composed of wheals (transient edematous papules and plaques, usually pruritic and caused by edema of the papillary dermis) (Figs. 14-1 and 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 Diagnosis and Differential Diagnosis).There are some syndromes with angioedema in which urticarial wheals are rarely present (e.g., hereditary angioedema). SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/28 UR - accessmedicine.mhmedical.com/content.aspx?aid=1199570637 ER -