Definition: Urticaria is defined as the appearance of wheals caused by a specific stimulus. A hive, or wheal, is a circular, red, spongy lesion that evolves and changes over minutes to hours. It is usually surrounded by an area of redness called a flare. Urticaria can vary in size from a few millimeters to giant lesions covering a whole extremity.
Urticaria results from dilation of capillaries allowing fluid to leak out into the surrounding tissue, the epidermis. The lesions resolve when the body absorbs this fluid. The border of a hive is described as polycyclic, or made up of many circles, and changes as fluid leaks out and then is absorbed. Pressing on a hive causes the skin to blanch distinguishing it from a bruise or papule.
Hives Pictures
Pronunciation: ur-ti-CARE-ee-uh - (noun)
Also Known As: Hives, wheals, whelts, angioedema
Common Misspellings: whelps
