Normal healthy child developing psoriatic lesions after an episode of streptococcal infection. Which type of lesion is this?
**Koebner Phenomenon**
**Core Concept**
The Koebner phenomenon refers to the development of psoriatic lesions in response to skin trauma or infection, such as streptococcal infection. It is a classic example of a precipitating factor in psoriasis, a chronic autoimmune skin condition characterized by erythematous plaques and silvery scales.
**Why the Correct Answer is Right**
The correct answer is related to the Koebner phenomenon, where the skin of a patient with psoriasis reacts to the streptococcal infection by developing new lesions. This is thought to be due to the activation of immune cells, such as T-cells, in response to the infection, leading to inflammation and the characteristic psoriatic lesion. The exact mechanism is not fully understood, but it is believed to involve the release of cytokines and chemokines that recruit immune cells to the affected area.
**Why Each Wrong Option is Incorrect**
* **Option A:** Not applicable, as the question is asking for a type of lesion.
* **Option B:** Not correct, as this option does not relate to the Koebner phenomenon or psoriasis.
* **Option C:** Not correct, as this option does not describe a type of lesion associated with the Koebner phenomenon.
**Clinical Pearl / High-Yield Fact**
The Koebner phenomenon can be a diagnostic clue in patients with psoriasis, as it can help identify individuals who are more likely to develop new lesions in response to skin trauma or infection. It is essential to consider this phenomenon in patients with psoriasis who present with new lesions, especially in the context of a recent streptococcal infection.
**Correct Answer:** C.