What is a characteristic of psoriatic arthritis?

• A. Joint stiffness in the morning
• B. Distal tuft resorption and pencil-in-cup deformities
• C. Localized swelling in the knees
• D. Systemic symptoms like fever

Answer: (B)

Psoriatic arthritis is characterized by distinct bone changes, particularly evident in imaging studies. One hallmark feature is distal tuft resorption and pencil-in-cup deformities. These changes occur at the ends of the fingers and toes, where the bone becomes eroded or resorbed, leading to the characteristic "pencil-in-cup" appearance on X-rays. This is due to the interplay of inflammation and bone remodeling associated with the disease.

Other options, while they may relate to various types of arthritis or joint conditions, do not specifically define psoriatic arthritis. Morning joint stiffness can be a feature of many types of inflammatory arthritis, and localized swelling in the knees might not be exclusive to psoriatic arthritis either. Similarly, systemic symptoms like fever are more common in other inflammatory conditions rather than being a primary characteristic of psoriatic arthritis. Therefore, the presence of distal tuft resorption and pencil-in-cup deformities is a defining characteristic of psoriatic arthritis, reflecting the unique pathophysiological changes that occur within this condition.