Wheal
Pronunciation: weel
A transient, raised, pale oedematous plaque on the skin with surrounding erythema, characteristic of urticarial reactions.
Full Definition
A wheal is the primary lesion of urticaria: a superficial, oedematous, pale-centred elevation of the skin surrounded by a flare of erythema, caused by histamine-mediated dermal oedema. Wheals are typically pruritic, appear within minutes, and resolve within 24 hours without leaving marks. They range from a few millimetres to several centimetres ('giant urticaria') and are used in allergy testing (wheal-and-flare response) to grade sensitisation. Editors must note that 'wheal' is the correct dermatological spelling, distinct from 'weal' (a raised mark from a blow) and 'welt,' both of which are common lay variants. Confusion with 'wheel' is a frequent typographical error.
Usage
Usage note: Always use 'wheal' in clinical dermatology; flag 'weal' or 'welt' as lay usage and query the author in formal documents.
In Context
- "Skin-prick testing produced a wheal of 8 mm with a surrounding flare of 15 mm to house dust mite allergen." — Allergy test report
- "The proofreader corrected 'wheel' to 'wheal' in three instances within the urticaria case series." — Proofreading note