Which secondary lesion results from mechanical abrasion of the epidermis or injury to the epidermis, such as scratching an insect bite?

• A. Excoriation
• B. Crust
• C. Pustule
• D. Vesicle

Answer: (A)

Mechanical abrasion of the epidermis produces an excoriation. This is a superficial scratch or removal of the outer skin layer, which commonly happens when you scratch an insect bite. It’s a secondary lesion because it results from physical trauma to the skin rather than being the initial lesion type itself. Crust forms from dried exudate over a lesion, not from abrasion of the epidermis; pustule and vesicle are primary lesions representing fluid-filled spaces or pus, not damage from scratching. Thus excoriation best fits the scenario of scratching an insect bite.