What term describes new psoriatic plaques that form at sites of skin trauma?

What term describes new psoriatic plaques that form at sites of skin trauma?

• A. Auspitz sign
• B. Nikolsky sign
• C. Koebner phenomenon
• D. Darier sign

Answer: (C)

The idea being tested is how skin trauma can trigger new psoriatic plaques in people who are susceptible, a pattern called the Koebner phenomenon. In psoriasis, injury from scratching, sunburn, surgery, or friction can provoke a local immune response that drives keratinocyte proliferation and inflammation, leading to new plaques appearing right at the damaged skin. This is why patients sometimes notice fresh patches after an injury. The other terms describe different skin findings not about trauma-induced plaque formation: for example, a sign where removing scales causes pinpoint bleeding, a sign where superficial skin layers separate with gentle pressure in certain blistering disorders, and a urticarial reaction triggered by rubbing, respectively.

The idea being tested is how skin trauma can trigger new psoriatic plaques in people who are susceptible, a pattern called the Koebner phenomenon. In psoriasis, injury from scratching, sunburn, surgery, or friction can provoke a local immune response that drives keratinocyte proliferation and inflammation, leading to new plaques appearing right at the damaged skin. This is why patients sometimes notice fresh patches after an injury. The other terms describe different skin findings not about trauma-induced plaque formation: for example, a sign where removing scales causes pinpoint bleeding, a sign where superficial skin layers separate with gentle pressure in certain blistering disorders, and a urticarial reaction triggered by rubbing, respectively.