Which feature is a hallmark of psoriasis when scales are removed?

• A. Auspitz sign
• B. Koebner response
• C. Nail pitting
• D. Dermal atrophy

Answer: (A)

Removing scales from a psoriasis plaque often reveals tiny pinpoint bleeds in the underlying dermal papillae, known as the Auspitz sign. This happens because psoriasis causes dilated capillaries in the papillae and thinning of the overlying epidermis, so lifting the scale exposes these vessels and they bleed in small, precise spots. This bleeding after scale removal is a classic clue pointing to psoriasis. The Koebner phenomenon is about new lesions appearing at sites of skin trauma, not bleeding when scales are removed. Nail pitting and dermal atrophy are not the defining sign you’d rely on to identify psoriasis from scale removal alone; they’re separate or less specific features.