## **Core Concept**
The question pertains to a clinical sign specific to psoriasis, a chronic autoimmune skin condition characterized by rapid skin cell growth leading to thick, red, and scaly patches. The sign in question is related to the appearance of bleeding points upon removal of scales from psoriatic lesions.

## **Why the Correct Answer is Right**
The correct answer, **Auspitz's sign**, is a well-known clinical feature of psoriasis. When scales are gently scraped off from a psoriatic plaque, tiny bleeding spots appear due to the thinning of the epidermis over the dermal papillae and the dilated, tortuous capillaries that lie close to the surface. This occurs because the psoriatic plaque exhibits an absence of the normal granular layer and stratum corneum, leading to a diminished barrier between the capillaries and the skin surface.

## **Why Each Wrong Option is Incorrect**
- **Option B:** While Nikolsky's sign is a dermatological test, it involves gentle pressure on the skin to remove the outer layer, typically positive in conditions like pemphigus vulgaris and staphylococcal scalded skin syndrome, not specifically related to bleeding spots in psoriasis.
- **Option C:** Darier's sign is associated with mastocytosis and involves dermographic urticaria where stroking the skin results in a wheal; not related to psoriasis or bleeding spots.
- **Option D:** The other options do not directly relate to a known sign associated with the described phenomenon in psoriasis.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that Auspitz's sign, while not pathognomonic, is highly suggestive of psoriasis. It's an important diagnostic clue that can be elicited during a physical examination. Remember, the presence of this sign indicates the characteristic vascular changes and epidermal thinning seen in psoriatic lesions.

## **Correct Answer:** . Auspitz's sign