Assessment of urticaria

Urticaria, also known as welts, hives, or wheals, is characterised by the appearance of intensely pruritic erythematous plaques. It appears clinically as pruritic, pale, blanching swellings of the superficial dermis that last for up to 24 hours. [Figure caption and citation for the preceding image starts]: Acute urticaria: typical wheals From the collection of Adam Reich, MD, PhD [Citation ends]. [Figure caption and citation for the preceding image starts]: Typical lesions seen in acute or chronic urticaria From the collection of Stephen Dreskin, MD, PhD [Citation ends]. [Figure caption and citation for the preceding image starts]: Urticaria: wheals From the collection of Adam Reich, MD, PhD [Citation ends]. Lesions may be small, large, giant, oval, or annular.

Urticaria affects 10% to 25% of the population and can occur in any age group. [1] Guldbakke KK, Khachemoune A. Etiology, classification, and treatment of urticaria. Cutis. 2007;79:41-49. http://www.ncbi.nlm.nih.gov/pubmed/17330621?tool=bestpractice.com It is a mast cell driven disease. The triggering mechanisms for mast-cell activation in urticaria are not well defined but seem to be multiple and diverse. [2] Zuberbier T, Aberer W, Asero R, et al; European Academy of Allergy and Clinical Immunology; Global Allergy and Asthma European Network; European Dermatology Forum; World Allergy Organization. The EAACI/GA2LEN/EDF/WAO guideline for the definition, classification, diagnosis, and management of urticaria: the 2013 revision and update. Allergy. 2014;69:868-887. http://onlinelibrary.wiley.com/doi/10.1111/all.12313/full http://www.ncbi.nlm.nih.gov/pubmed/24785199?tool=bestpractice.com Urticaria is classified according to duration of symptoms:

• Acute urticaria: the occurrence of spontaneous wheals, angio-oedema, or both for <6 weeks [1] Guldbakke KK, Khachemoune A. Etiology, classification, and treatment of urticaria. Cutis. 2007;79:41-49. http://www.ncbi.nlm.nih.gov/pubmed/17330621?tool=bestpractice.com [2] Zuberbier T, Aberer W, Asero R, et al; European Academy of Allergy and Clinical Immunology; Global Allergy and Asthma European Network; European Dermatology Forum; World Allergy Organization. The EAACI/GA2LEN/EDF/WAO guideline for the definition, classification, diagnosis, and management of urticaria: the 2013 revision and update. Allergy. 2014;69:868-887. http://onlinelibrary.wiley.com/doi/10.1111/all.12313/full http://www.ncbi.nlm.nih.gov/pubmed/24785199?tool=bestpractice.com [3] Bernstein JA, Lang DM, Khan DA, et al. The diagnosis and management of acute and chronic urticaria: 2014 update. J Allergy Clin Immunol. 2014;133:1270-1277. http://www.ncbi.nlm.nih.gov/pubmed/24766875?tool=bestpractice.com

• Chronic urticaria: urticaria that has been continuously or intermittently present for at least 6 weeks. [3] Bernstein JA, Lang DM, Khan DA, et al. The diagnosis and management of acute and chronic urticaria: 2014 update. J Allergy Clin Immunol. 2014;133:1270-1277. http://www.ncbi.nlm.nih.gov/pubmed/24766875?tool=bestpractice.com

Chronic urticaria has been classified into the following 2 subtypes: [2] Zuberbier T, Aberer W, Asero R, et al; European Academy of Allergy and Clinical Immunology; Global Allergy and Asthma European Network; European Dermatology Forum; World Allergy Organization. The EAACI/GA2LEN/EDF/WAO guideline for the definition, classification, diagnosis, and management of urticaria: the 2013 revision and update. Allergy. 2014;69:868-887. http://onlinelibrary.wiley.com/doi/10.1111/all.12313/full http://www.ncbi.nlm.nih.gov/pubmed/24785199?tool=bestpractice.com

• Chronic spontaneous urticaria: spontaneous appearance of wheals, angio-oedema, or both ≥6 weeks due to known or unknown causes.

• Inducible urticaria, for example delayed pressure urticaria, heat urticaria, solar urticaria, symptomatic dermatographism, vibratory angio-oedema, aquagenic urticaria, cholinergic urticaria, and contact urticaria.

Some people have urticaria that is complicated by angio-oedema, a swelling of the deeper dermis and tissues (e.g., mucosal surfaces), with laryngeal oedema potentially causing respiratory distress and death. [2] Zuberbier T, Aberer W, Asero R, et al; European Academy of Allergy and Clinical Immunology; Global Allergy and Asthma European Network; European Dermatology Forum; World Allergy Organization. The EAACI/GA2LEN/EDF/WAO guideline for the definition, classification, diagnosis, and management of urticaria: the 2013 revision and update. Allergy. 2014;69:868-887. http://onlinelibrary.wiley.com/doi/10.1111/all.12313/full http://www.ncbi.nlm.nih.gov/pubmed/24785199?tool=bestpractice.com Angio-oedema is commonly associated with urticaria and may occur at any age. [4] Katelaris CH, Peake JE. MJA practice essentials 5. Allergy and the skin: eczema and chronic urticaria. Med J Aust. 2006;185:517-522. http://www.mja.com.au/public/issues/185_09_061106/kat10399_fm.html http://www.ncbi.nlm.nih.gov/pubmed/17137459?tool=bestpractice.com [Figure caption and citation for the preceding image starts]: Angio-oedema of the lips in a patient who also has urticaria From the collection of Stephen Dreskin, MD, PhD [Citation ends]. It may not necessarily be seen at the first urticarial episode, and its risk increases with greater exposure to the allergenic substance. [5] Grattan CEH, Black AK. Urticaria and angioedema. In: Bolognia JL, Jorizzo JL, Rapini RP ed. Dermatology (volume one). London, UK: Mosby; 2003;287-302. Symptoms are typically numbness, pain, or paraesthesias. [6] Kwong KY, Maalouf N, Jones CA. Urticaria and angioedema: pathophysiology, diagnosis, and treatment. Pediatr Ann. 1998;27:719-724. http://www.ncbi.nlm.nih.gov/pubmed/9826877?tool=bestpractice.com Angio-oedema without urticaria should prompt further evaluation.