Appearance
Wheals (raised areas surrounded by a red base) from urticaria can appear anywhere on the surface of the skin. Whether the trigger is allergic or not, a complex release of inflammatory mediators, including histamine from cutaneous mast cells, results in fluid leakage from superficial blood vessels. Wheals may be pinpoint in size, or several inches in diameter.
Angioedema is a related condition (also from allergic and nonallergic causes), though fluid leakage is from much deeper blood vessels in the subcutaneous or submucosal layers. Individual hives that are painful, last more than 24 hours, or leave a bruise as they heal are more likely to be a more serious condition called urticarial vasculitis. Hives caused by stroking the skin (often linear in appearance) are due to a benign condition called dermatographic urticaria.
Read more about this topic: Acute Urticaria
Famous quotes containing the word appearance:
“The actor is too prone to exaggerate his powers; he wants to play Hamlet when his appearance is more suitable to King Lear.”
—Sarah Bernhardt (1845–1923)
“When appearance and reality coincide, philosophy and literary criticism find themselves with nothing to say.”
—Mason Cooley (b. 1927)
“The whole appearance is a toy. For this,
The dove in the belly builds his nest and coos,
Selah, tempestuous bird. How is it that
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Like excellence collecting excellence?”
—Wallace Stevens (1879–1955)