This rare form is triggered by stress and is characterized by wheals surrounded by a white vasoconstrictive halo, a different trigger and morphology than cholinergic urticaria.
This is triggered by contact with water, regardless of its temperature, whereas cholinergic urticaria is triggered by a rise in core body temperature (heat, exercise).
This is distinguished by the appearance of deep, often painful swelling that is delayed by several hours after sustained pressure has been applied to the skin.
