What is the primary characteristic of a keloid?

The primary characteristic of a keloid is that it is a raised scar resulting from excessive collagen formation. Keloids occur when the wound healing process goes awry, leading to an overproduction of collagen fibers which protrude above the surrounding skin. This can create a thick, raised area that may expand beyond the original site of injury.

Keloids are typically more prominent than normal scars, and they can vary in color, size, and texture. They may also cause discomfort or itchiness in some individuals. Understanding the nature of keloids is essential because they can pose challenges in treatment, as they are resistant to conventional scar management practices.

The other options focus on different skin conditions or characteristics that are not related to keloids. For instance, skin infection is a separate issue involving pathogens, while hyperpigmentation refers to the darkening of the skin rather than a physical scar. Acne scarring is specifically related to scars left by acne lesions and follows different mechanisms of skin healing. Thus, the distinctive feature of keloids lies in their excess collagen production leading to raised scarring.