**Question:** Which of the following seen in Psoriasis -

A. Hyperkeratosis
B. Erythema
C. Papules
D. Nail involvement

**Core Concept:**
Psoriasis is a chronic inflammatory autoimmune disorder characterized by accelerated skin cell production leading to red, scaly plaques on the skin. It is a type of dermatological condition.

**Why the Correct Answer is Right:**
Psoriasis is primarily characterized by hyperkeratosis, which is an overproduction of keratinocytes, causing thickening of the skin and formation of plaques. The other options are also commonly seen in psoriasis but are not the primary feature. Erythema (redness) is a secondary response to inflammation. Papules are small, elevated, and tender bumps on the skin, which can be present in psoriasis, but they are not the primary feature. Nail involvement (onychodysplasia) is also a feature of psoriasis, but it is a separate entity and not the primary feature of the disease.

**Why Each Wrong Option is Incorrect:**
Erythema (B) is a secondary response to inflammation but not the primary feature of psoriasis.

Papules (C) are small, elevated, and tender bumps on the skin, which can be present in psoriasis, but they are not the primary feature.

Nail involvement (D) is present in psoriasis, but it is a separate entity and not the primary feature of the disease.

**Clinical Pearl:**
Psoriasis is a complex disease involving immune system dysregulation, and understanding its core features (hyperkeratosis, nail involvement) is essential for accurate diagnosis and management of the condition.