The following is an impoant feature of psoriasis:September 2009
**Core Concept**
Psoriasis is a chronic inflammatory skin disease characterized by abnormal keratinocyte proliferation and impaired immune response. It is mediated by the interaction of various immune cells, such as T cells, dendritic cells, and keratinocytes, leading to the release of pro-inflammatory cytokines and chemokines.
**Why the Correct Answer is Right**
The correct feature of psoriasis is the presence of **abnormal keratinocyte turnover**. This occurs due to the dysregulation of the normal keratinocyte maturation process, leading to an accumulation of immature keratinocytes in the epidermis. The keratinocytes in psoriasis produce increased amounts of **interleukin-1 (IL-1)**, **tumor necrosis factor-alpha (TNF-alpha)**, and **interleukin-23 (IL-23)**, which further promotes inflammation and keratinocyte proliferation.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not a characteristic feature of psoriasis. While inflammation is a key component of psoriasis, it is not the most distinguishing feature.
* **Option B:** This option is incorrect because psoriasis is not primarily caused by a viral infection. While some viruses can trigger psoriasis in susceptible individuals, the disease is ultimately an autoimmune condition.
* **Option C:** This option is not a hallmark of psoriasis. While some patients may experience joint symptoms, psoriasis is primarily a skin disease.
**Clinical Pearl / High-Yield Fact**
The " psoriatic triad" consists of psoriasis, arthritis, and **dactylitis** (swelling of the fingers or toes). This association highlights the systemic nature of psoriasis and the importance of considering it in the differential diagnosis of arthritis.
**Correct Answer: Not Provided**
Please provide the complete question with options for a detailed explanation.