What is an example of a wheal or hive?

• A. Eczema
• B. Urticaria
• C. Psoriasis
• D. Contact dermatitis

Answer: (B)

Wheals or hives are raised, well-defined spots in the skin that appear suddenly, are intensely itchy, and usually blanch when pressed. They occur in urticaria because of mast cell degranulation and histamine release in the superficial dermis, which causes localized edema and dilation of small vessels. Each individual wheal lasts a short time, but new ones can appear as old ones fade, giving the sensation of a shifting, changing rash.

This pattern distinguishes urticaria from other common skin conditions. Eczema (atopic dermatitis) presents with itchy, red, swollen patches that may ooze or crust and often show chronic changes like thickening. Psoriasis shows well-demarcated red plaques with silvery scales. Contact dermatitis is an inflammatory reaction at the site of contact with an irritant or allergen and may include vesicles or oozing in that area.