Which of the following describes a wheal?

A wheal is characterized as a raised red skin lesion that occurs due to the accumulation of interstitial fluid in the dermis. This swelling is often a result of an allergic reaction, irritation, or pressure. Wheals typically present with a pale center and red surrounding area, and they can vary in shape and size. Conditions such as hives or urticaria commonly feature wheals, which can appear suddenly and may itch or be uncomfortable.

In contrast, a flat red rash due to allergens is a different manifestation, as it is not raised and usually indicative of a different type of reaction. Pustular skin infections involve the formation of pus and are associated with infectious processes. Harmless skin discolorations do not usually involve swelling or inflammation, hence diverging from the definition of a wheal. Understanding the specific characteristics of wheals aids in their identification and distinguishes them from other types of skin lesions.