Urticaria, also known as welts, hives, or wheals, is characterised by the appearance of intensely pruritic erythematous plaques.[1]Bernstein JA, Lang DM, Khan DA, et al. The diagnosis and management of acute and chronic urticaria: 2014 update. J Allergy Clin Immunol. 2014 May;133(5):1270-7.
http://www.ncbi.nlm.nih.gov/pubmed/24766875?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]European Dermatology Forum. The international EAACI/GA²LEN/EuroGuiDerm/APAAACI guideline for the definition, classification, diagnosis, and management of urticaria. Sep 2021 [internet publication].
https://www.guidelines.edf.one//uploads/attachments/cl263w4y200oilajn3li6nqa1-urticaria-2021-gl.pdf
Urticaria is classified according to duration of symptoms:
Acute urticaria: the occurrence of spontaneous wheals, angio-oedema, or both for <6 weeks[1]Bernstein JA, Lang DM, Khan DA, et al. The diagnosis and management of acute and chronic urticaria: 2014 update. J Allergy Clin Immunol. 2014 May;133(5):1270-7.
http://www.ncbi.nlm.nih.gov/pubmed/24766875?tool=bestpractice.com
[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]European Dermatology Forum. The international EAACI/GA²LEN/EuroGuiDerm/APAAACI guideline for the definition, classification, diagnosis, and management of urticaria. Sep 2021 [internet publication].
https://www.guidelines.edf.one//uploads/attachments/cl263w4y200oilajn3li6nqa1-urticaria-2021-gl.pdf
Chronic urticaria: urticaria that has been continuously or intermittently present for ≥6 weeks.[1]Bernstein JA, Lang DM, Khan DA, et al. The diagnosis and management of acute and chronic urticaria: 2014 update. J Allergy Clin Immunol. 2014 May;133(5):1270-7.
http://www.ncbi.nlm.nih.gov/pubmed/24766875?tool=bestpractice.com
[3]European Dermatology Forum. The international EAACI/GA²LEN/EuroGuiDerm/APAAACI guideline for the definition, classification, diagnosis, and management of urticaria. Sep 2021 [internet publication].
https://www.guidelines.edf.one//uploads/attachments/cl263w4y200oilajn3li6nqa1-urticaria-2021-gl.pdf
[4]Sabroe RA, Lawlor F, Grattan CEH, et al. British Association of Dermatologists guidelines for the management of people with chronic urticaria 2021. Br J Dermatol. 2022 Mar;186(3):398-413.
https://academic.oup.com/bjd/article/186/3/398/6705777
http://www.ncbi.nlm.nih.gov/pubmed/34773650?tool=bestpractice.com
Chronic urticaria is classified into 2 subtypes:[3]European Dermatology Forum. The international EAACI/GA²LEN/EuroGuiDerm/APAAACI guideline for the definition, classification, diagnosis, and management of urticaria. Sep 2021 [internet publication].
https://www.guidelines.edf.one//uploads/attachments/cl263w4y200oilajn3li6nqa1-urticaria-2021-gl.pdf
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.
Urticaria complicated by angio-oedema
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]European Dermatology Forum. The international EAACI/GA²LEN/EuroGuiDerm/APAAACI guideline for the definition, classification, diagnosis, and management of urticaria. Sep 2021 [internet publication].
https://www.guidelines.edf.one//uploads/attachments/cl263w4y200oilajn3li6nqa1-urticaria-2021-gl.pdf
Angio-oedema is commonly associated with urticaria and may occur at any age.[5]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, but risk of angio-oedema increases with greater exposure to the allergenic substance.[6]Grattan CEH, Black AK. Urticaria and angioedema. In: Bolognia JL, Jorizzo JL, Rapini RP ed. Dermatology (volume one). London, UK: Mosby; 2003;287-302.
Clinical presentation of angio-oedema may include non-pitting oedema of the subcutaneous tissues involving lips, face, neck and extremities and/or submucosal tissues affecting the oral cavity, larynx and gastrointestinal system.[7]Depetri F, Tedeschi A, Cugno M. Angioedema and emergency medicine: From pathophysiology to diagnosis and treatment. Eur J Intern Med. 2019 Jan;59:8-13.
http://www.ncbi.nlm.nih.gov/pubmed/30220453?tool=bestpractice.com
Associated symptoms may also be present. These are dependent on the underlying aetiology. Examples include flushing, bronchospasm, abdominal pain, diarrhoea and vomiting.[7]Depetri F, Tedeschi A, Cugno M. Angioedema and emergency medicine: From pathophysiology to diagnosis and treatment. Eur J Intern Med. 2019 Jan;59:8-13.
http://www.ncbi.nlm.nih.gov/pubmed/30220453?tool=bestpractice.com
Angio-oedema without urticaria should prompt further evaluation.[1]Bernstein JA, Lang DM, Khan DA, et al. The diagnosis and management of acute and chronic urticaria: 2014 update. J Allergy Clin Immunol. 2014 May;133(5):1270-7.
http://www.ncbi.nlm.nih.gov/pubmed/24766875?tool=bestpractice.com
[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].