**Question:** True about psoriatic arthritis are all expect -

A. It is an autoimmune disorder.
B. It primarily affects the skin.
C. It is characterized by inflammation.
D. It is a result of poor lifestyle choices.

**Core Concept:** Psoriatic arthritis is a type of inflammatory arthritis that commonly occurs in patients with psoriasis, a skin condition characterized by the overproduction of skin cells. Psoriatic arthritis is an autoimmune disorder, where the body's immune system mistakenly attacks its own tissues, causing inflammation and damage to joints.

**Why the Correct Answer is Right:** Option D is incorrect because psoriatic arthritis is not solely a result of poor lifestyle choices, such as diet or lack of exercise. While some lifestyle factors might exacerbate the condition, it is primarily an autoimmune disorder.

**Why Each Wrong Option is Incorrect:**

A. While psoriasis is a skin condition associated with psoriatic arthritis, it is not limited to it. Psoriasis can manifest independently without arthritis.
B. Psoriatic arthritis does affect the skin to some extent, but the primary focus is on joint inflammation and damage.
C. The correct answer (psoriatic arthritis being characterized by inflammation) is supported by the autoimmune nature of the condition and the involvement of joints.

**Clinical Pearl:** Psoriatic arthritis is often misdiagnosed as rheumatoid arthritis, as both conditions present with joint inflammation and may share some clinical features. However, distinguishing between the two is crucial for appropriate treatment, as the management strategies differ. For example, psoriatic arthritis may require biologic agents, while rheumatoid arthritis may require non-biologic disease-modifying antirheumatic drugs (DMARDs).

**Correct Answer:** C. Psoriatic arthritis is characterized by inflammation, as it is an autoimmune disorder leading to joint inflammation and damage.