A localized shedding of epithelium is best described by which term?

• A. Erosion
• B. Ulcer
• C. Crust
• D. Scar

Answer: (B)

Understanding how deep tissue loss goes when epithelium is shed is what this question tests. Erosion describes a shallow loss that affects only the surface epithelium and does not extend into the underlying tissue; such lesions typically heal without scarring. An ulcer, by contrast, is a deeper defect in which the epithelium has been lost and underlying tissue is exposed, creating a crater-like area that goes beyond just the surface and often heals with scar formation. A crust is just dried exudate on the surface, not tissue loss, and a scar is fibrous tissue that forms after healing, not the initial lesion. Since the description implies tissue loss that extends below the surface, the term that fits best is ulcer.