Acne scars can form as a result of inflamed acne blemishes, or picking at any acne lesions.
Inflammatory acne is caused when the oil gland/hair follicle unit becomes overloaded with excess oil, dead skin cells and bacteria. The unit swells, which causes a break in the follicle wall. If the lesion is shallow, it can possibly heal quickly. However, if there is a deep break in the unit wall, infected material can spill out into the surrounding tissue and create a deeper lesion. The skin attempts to repair these lesions by forming new collagen fibers. These repairs are not as smooth and flawless as the original skin, resulting in acne scarring.
Additionally, picking at any acne lesions and causing scabs that are repeatedly torn from the skin can lead to scarring.
Almost 95% of patients with acne will experience some form of acne scarring. There are no specific risk factors, but some believe genetics plays a role.
There are two main types of acne scars:
Hypertrophic or keloid scarring develops when the body produces too much collagen as acne wounds heal, resulting in a mass of raised tissue on the skin's surface.
Atrophic or depressed scarring develops when there is a loss of tissue. There are two common types of atrophic scarring. "Icepick" scars which are usually small, yet obvious holes in the skin. And "boxcar" scars which are depressed areas, usually round or oval in shape with steeply angled sides, similar to chickenpox scars.
Physical examination is needed to diagnose the type of scarring and develop the most appropriate treatment plan.
American Academy of Dermatology American Society for Dermatologic Surgery