**Question:** Koebner's phenomenon is seen in which of the following conditions?

A. Lichen planus
B. Warts
C. Bechet syndrome
D. Psoriasis
E. Viggo

**Correct Answer:** D. Psoriasis

**Core Concept:** Koebner's phenomenon, also known as the dermatological response to injury, is a phenomenon wherein the presence of a dermatological condition leads to the development of lesions in a non-affected area of the skin upon injury. This phenomenon was first described by Heinrich Koebner in 1878.

**Why the Correct Answer is Right:** Koebner's phenomenon is primarily seen in psoriasis, a chronic inflammatory skin disorder characterized by rapid skin cell growth, leading to the formation of red, scaly patches (plaques). When a person with psoriasis experiences trauma (injury) to their skin, such as a cut or abrasion, the affected area may develop psoriatic lesions, demonstrating the phenomenon described by Koebner.

**Why Each Wrong Option is Incorrect:**

A. Lichen planus: This is a different dermatological condition characterized by flat, bluish-purple papules arranged in a reticulated pattern, typically involving the extremities and flexural areas. It is not associated with Koebner's phenomenon.

B. Warts: Warts are caused by the human papillomavirus (HPV) infection and are benign skin growths, not associated with Koebner's phenomenon.

C. Bechet syndrome: This is a rare, complex, inflammatory disorder involving multiple organ systems, including the gastrointestinal, ocular, and central nervous systems. Koebner's phenomenon is not a feature of Bechet syndrome.

E. Viggo: This option appears to be a typo or irrelevant term and does not relate to any dermatological phenomenon or condition.

**Clinical Pearl:** Koebner's phenomenon highlights the complex interplay between skin injury and immune response in dermatological conditions, emphasizing the importance of understanding the underlying mechanisms and clinical manifestations of various skin diseases.