Which condition presents with red plaques featuring silvery-white scales and sharp margins?

The condition that presents with red plaques featuring silvery-white scales and sharp margins is psoriasis. This chronic inflammatory skin condition is characterized by its well-defined, raised erythematous plaques that are covered with silvery scales. These plaques can occur anywhere on the body but are commonly found on the elbows, knees, scalp, and lower back.

Psoriasis occurs due to an accelerated proliferation of keratinocytes, leading to an excess of skin cell turnover. The sharp margins of the plaques are a distinctive feature that helps differentiate psoriasis from other skin conditions. Additionally, the silvery scales are created by the accumulation of dead skin cells and are a key diagnostic feature.

In contrast, eczema is generally characterized by itchy, inflamed skin that can be red and scaly, but it tends to have less distinct margins and does not typically present with silvery scales. Contact dermatitis results from exposure to irritants or allergens and usually appears as localized redness and swelling rather than well-defined plaques. Allergic reactions can also cause red, possibly raised areas on the skin but without the characteristic scaling seen in psoriasis.