Acnes are formed when oil, bacteria and dead cells get stuck below the skin's surface, stimulating oil secretion due to hormones.
 
Improper treatment of acnes, such as inappropriate cleaning, inflammation treatment or squeezing the acnes will leave scars. As the skin and fingers are not sterilized, touching the acnes may worsen the situation. Most patients cannot identify the types and severity of acnes, along with unprofessional techniques, patients may damage the true skin layer, causing enlarged pores or even indentations.
 
Due to vasodilation during inflammation, the vessels will remain dilated for a period of time, causing redness on the face, which will fade gradually by itself.
Some acnes will cause pigmentation after inflammation, which leave brown or black patches of colors on the face. In general the pigmentations will fade gradually for over a year.
Severe acne may damage massive amount of the collagen in dermis, causing indentations on the surface, and the larger indentations are called ice picks. Once they are formed, they cannot be removed.
The fibroblasts in the skin are activated to produce collagen for repairing once the dermis is injured. However, in some cases, the over-production of collagen will cause a protruding scarring on the skin. These scars normally will remain in that shape without any further growth.
Keloid is even more protruding then hypertrophic scaring. It may grow out of the original scar and stretch out. It may also cause itchiness and pain.
 
Although there is nothing to be done with genetic cause of acnes, the following steps may help you maintaining healthy skin.