Which of the following is a tissue sign seen in allergic reactions?

• A. Urticaria
• B. Erythema
• C. Pruritus
• D. Angioedema

Answer: (D)

Allergic reactions can produce signs that involve different layers of tissue. The sign that indicates swelling of deeper tissues—such as the lips, face, tongue, or even airway structures—is angioedema. This occurs when increased vascular permeability allows fluid to accumulate in subcutaneous or mucosal tissues, producing visible swelling that’s a true tissue sign. In contrast, urticaria refers to superficial skin wheals from dermal edema plus itching, erythema is redness from superficial vasodilation, and pruritus is the itching sensation. So the deep tissue swelling characteristic of angioedema makes it the best match for a tissue sign in this context.