Assessment of urticaria

Urticaria, also known as welts, hives, or wheals, is characterised by the appearance of intensely pruritic erythematous plaques.[1]Schaefer P. Acute and chronic urticaria: evaluation and treatment. Am Fam Physician. 2017 Jun 1;95(11):717-24. https://www.aafp.org/afp/2017/0601/p717.html http://www.ncbi.nlm.nih.gov/pubmed/28671445?tool=bestpractice.com It appears clinically as pruritic, pale, blanching swellings of the superficial dermis that last for up to 24 hours. Lesions may be small, large, giant, oval, or annular.[Figure caption and citation for the preceding image starts]: Acute urticaria: typical whealsFrom 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 urticariaFrom the collection of Stephen Dreskin, MD, PhD [Citation ends].[Figure caption and citation for the preceding image starts]: Urticaria: whealsFrom the collection of Adam Reich, MD, PhD [Citation ends].

Urticaria affects 10% to 25% of the population and can occur in any age group.[2]Guldbakke KK, Khachemoune A. Etiology, classification, and treatment of urticaria. Cutis. 2007 Jan;79(1):41-9. 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.[3]Zuberbier T, Aberer W, Asero R, et al. The EAACI/GA(2)LEN/EDF/WAO guideline for the definition, classification, diagnosis and management of urticaria. Allergy. 2018 Jul;73(7):1393-414. https://onlinelibrary.wiley.com/doi/full/10.1111/all.13397 http://www.ncbi.nlm.nih.gov/pubmed/29336054?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 or less[2]Guldbakke KK, Khachemoune A. Etiology, classification, and treatment of urticaria. Cutis. 2007 Jan;79(1):41-9. http://www.ncbi.nlm.nih.gov/pubmed/17330621?tool=bestpractice.com [3]Zuberbier T, Aberer W, Asero R, et al. The EAACI/GA(2)LEN/EDF/WAO guideline for the definition, classification, diagnosis and management of urticaria. Allergy. 2018 Jul;73(7):1393-414. https://onlinelibrary.wiley.com/doi/full/10.1111/all.13397 http://www.ncbi.nlm.nih.gov/pubmed/29336054?tool=bestpractice.com

• Chronic urticaria: urticaria that has been continuously or intermittently present for >6 weeks.[3]Zuberbier T, Aberer W, Asero R, et al. The EAACI/GA(2)LEN/EDF/WAO guideline for the definition, classification, diagnosis and management of urticaria. Allergy. 2018 Jul;73(7):1393-414. https://onlinelibrary.wiley.com/doi/full/10.1111/all.13397 http://www.ncbi.nlm.nih.gov/pubmed/29336054?tool=bestpractice.com

Chronic urticaria is classified into 2 subtypes:[3]Zuberbier T, Aberer W, Asero R, et al. The EAACI/GA(2)LEN/EDF/WAO guideline for the definition, classification, diagnosis and management of urticaria. Allergy. 2018 Jul;73(7):1393-414. https://onlinelibrary.wiley.com/doi/full/10.1111/all.13397 http://www.ncbi.nlm.nih.gov/pubmed/29336054?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.[3]Zuberbier T, Aberer W, Asero R, et al. The EAACI/GA(2)LEN/EDF/WAO guideline for the definition, classification, diagnosis and management of urticaria. Allergy. 2018 Jul;73(7):1393-414. https://onlinelibrary.wiley.com/doi/full/10.1111/all.13397 http://www.ncbi.nlm.nih.gov/pubmed/29336054?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 Nov 6;185(9):517-22. http://www.mja.com.au/public/issues/185_09_061106/kat10399_fm.html http://www.ncbi.nlm.nih.gov/pubmed/17137459?tool=bestpractice.com 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 Nov;27(11):719-24. http://www.ncbi.nlm.nih.gov/pubmed/9826877?tool=bestpractice.com Angio-oedema without urticaria should prompt further evaluation.[Figure caption and citation for the preceding image starts]: Angio-oedema of the lips in a patient who also has urticariaFrom the collection of Stephen Dreskin, MD, PhD [Citation ends].