Wheal

WHEAL (urtica, pustulus, anglic. - wheal, french. - plaque ortiee, german. - Quaddel), a raised, sharply defined disc of the most diverse shapes, firm to the touch, appearing suddenly and usually disappearing without a trace after several hours or days. Size ranges from a pea to the palm of the hand. Discs may merge, sometimes occupying extensive areas. Color¹ - pale pink, often with a white center and a pink peripheral rim. Sometimes a blister forms in the center of the disc. Wheals appear either at the site of scratches or spontaneously, usually accompanied by itching and burning. Histologically - hyperemia of the skin vessels, sometimes also of the subcutis, with rapid serous edema of the corium and sometimes the epidermis. Wheal - dermato-angioneurosis, caused by external agents (nettle, mosquito, jellyfish, caterpillar, etc.), circulation in the blood of a protein foreign to the body from food, products of improper assimilation, metabolism, worms, tissue breakdown, etc., as a result of which there is sensitization of the neurovascular apparatus of the skin, often accompanied by general disorders with hemoclastic shock.