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: Chronic Urticaria
Famous quotes containing the word appearance:
“Every natural fact is a symbol of some spiritual fact. Every appearance in nature corresponds to some state of the mind, and that state of the mind can only be described by presenting that natural appearance as its picture.”
—Ralph Waldo Emerson (1803–1882)
“To educate the wise man, the State exists; and with the appearance of the wise man, the State expires. The appearance of character makes the state unnecessary. The wise man is the State.”
—Ralph Waldo Emerson (1803–1882)
“Look into the world—how often do you behold a sordid wretch, whose straight heart is open to no man’s affliction, taking shelter behind an appearance of piety, and putting on the garb of religion, which none but the merciful and compassionate have a title to wear.”
—Laurence Sterne (1713–1768)