title: Pathology and classification of urticaria.
abstract: Chronic urticaria is defined as daily or almost daily urticaria for more than 6 weeks. Chronic urticaria is normally subdivided into physical urticaria (wheals evoked by a physical stimulus such as pressure friction or cold contact) and spontaneous urticaria. A patient with a history of less than 6 weeks is traditionally designated as having acute urticaria. Patients with chronic spontaneous urticaria have an increased frequency of HLA-DR and HLA-DQ alleles characteristically associated with autoimmune disease. Some of these patients have functional anti-FceR1 and/or anti-IgE autoantibodies which are considered to be the cause of the urticaria.
authors.affiliation: Cutaneous Allergy Clinic, St John's Institute of Dermatology, St Thomas' Hospital, Lambeth Palace Road, London SE1 7EH, UK; The London Allergy Clinic, 66 New Cavendish Street, London W1G 8TD, UK. Electronic address: mwatsong@hotmail.com.
authors.forename: Malcolm W
authors.initials: MW
authors.lastname: Greaves
mesh_terms: D015551:Autoimmunity; D001491:Basophils / Q000276:immunology / Q000378:metabolism; D020405:Dermis / Q000276:immunology / Q000473:pathology; D006801:Humans; D008407:Mast Cells / Q000276:immunology / Q000378:metabolism; D014581:Urticaria / Q000145:classification / Q000175:diagnosis* / Q000209:etiology*
keywords: Acute urticaria; Autoimmune urticaria; Chronic urticaria; Physical urticaria