Dark spots post-inflammatory hyperpigmentation & Raised Scars (hypertrophic)
Although technically not scars, black areas are an obvious sign of acne. Where acne has healed, the inflammatory process of acne can cause hyperpigmentation, or darker coloring.
Treatments for acne scars can potentially temporarily cause hyperpigmentation, especially in those with darker skin. Darker skin types may suffer post-inflammatory redness instead.
Sometimes too much collagen is produced by the skin when it recovers from acne. The result is raised scars that are caused by this. They typically appear on the back and chest.