Acne scars on the face, chest and back are very common. Some 80% of people between ages 11 and 30 will get acne, and one out of five of those people will develop scars. 

An acne lesion (pimple) grows when bacteria, oils and dead skin fill up and inflame pores, the tiny openings in your skin through which oil and sweat rise to the surface. Some 40,000 cells fall off your skin every hour but, sometimes, those dead cells clog up a pore. Sometimes clogged pores are small and result in "whiteheads or blackheads." Sometimes these pores become inflamed and lead to other types of acne. 

Types of acne 

Acne presents as many different forms. Whiteheads and blackheads are typical and tend to heal smoothly more often than not. Then there are the types that can lead to scarring:

• Papules: Pink to red bumps that hurt when you touch them.
• Pustules: Pus-filled lesions. They're red at the base and white or yellow at the top.
• Nodules: Solid lesions. They're larger than papules and pustules and can hurt more because they extend deeper into the skin.
• Cysts: Cysts lie deep within the skin. They're painful, full of pus and are most likely to scar.

How does acne cause scars?

Your skin is your largest organ. It has three main layers. They are, starting with the outermost, the epidermis, the dermis and the hypodermis. The layers protect your fragile insides from the elements, from UV rays and bacteria, and they also help produce vitamin D thanks to sunlight. Any area with sebaceous glands is prone to acne — especially the face, back and chest.

Acne scars are the result of inflammation of acne blemishes. The acne pore swells and a breakdown occurs in the wall of the pore. Some acne blemishes are small and the scars created are shallow and heal quickly. Sometimes the contents of blemishes spill into the surrounding tissue and cause deeper scars. The skin's response is to repair the scar by forming new collagen fibers.

Acne scars take on two main forms: either a scar develops when there is a loss of tissue, resulting in an indentation in the surface of the skin; or, a scar develops that is raised on the surface of the skin. This type of acne scar, in fact, is a sign that your skin is doing its job — but, perhaps, too well. Your skin creates collagen ("repair tissue") to help heal the wound — the acne — but, if it makes too much collagen, raised scars form.

Keep in mind that just because you have acne, that doesn't mean you'll get scars. And if you do (one in five people with acne will also have scarring), the good news is that not all acne scars are permanent! Treatments are available. Some treatments nearly remove the scars while others help the skin heal itself with its own collagen.