What best defines a wheal?

A wheal is best defined as a smooth, slightly elevated, swollen area that appears redder or paler than the surrounding skin. This characteristic is typically associated with allergic reactions and conditions like hives (urticaria), where the body releases histamines, leading to localized swelling and inflammation. Wheals are often temporary and can change in shape and size, differentiating them from more permanent skin lesions.

The other options describe different types of skin conditions. Flat, discolored lesions refer to macules or patches, which lack the elevation seen in wheals. A type of ulcer represents an open sore or lesion that penetrates the skin, which is a different skin condition entirely. A solid mass beneath the skin describes a nodule or tumor, rather than the temporary swelling associated with a wheal. Understanding these distinctions is crucial for accurate identification and treatment of skin conditions.