Acne Scars are a variety of depressed scars that have occurred due to loss of skin thickness from the body's inflammatory response to a plugged sebaceous follicle. The inflammatory reaction (infection) results in thinning of the skin even though scar tissue has formed. Acne scars appear in a variety of shapes, which are important to distinguish, as they are often treated differently.

Icepick scars are usually narrow (1 -2 mms), sharply demarcated tracts that are wider at the surface and taper as they extend through the skin. They usually go through the entire thickness of the skin.

Rolling scars are more superficial, wider, and produce an uneven appearance in the skin. They usually are the largest of the acne scars in diameter.

Boxcar scars are round- to oval-shaped skin dimples with sharp margins and are wider than icepick scars but not as wide as rolling scars. Most tend to have diameters from 2.0 - 4.0 mm.