Local heat urticaria.

We present a 38-year-old woman with local heat urticaria confirmed by heat provocation testing. Heat urticaria is a rare form of physical urticaria that istriggered by exposure to a heat source, such as hot water or sunlight. Although it is commonly localized and immediate, generalized and delayed onset forms exist. Treatment options include antihistamines and heat desensitization. A brisk, mechanical stroke elicited a linear wheal. Five minutes after exposure to hot water, she developed well-demarcated,erythematous blanching wheals that covered the distal forearm and entire hand.