^ White, Stephen D.; Bordeau, Patrick B.; Blumstein, Philippe; Ibisch, Catherine; GuaguÈre, Eric; Denerolle, Philippe; Carlotti, Didier N.; Scott, Katherine V. (1 September 1997). "Feline acne and results of treatment with mupirocin in an open clinical trial: 25 cases (1994–96)". Veterinary Dermatology. 8 (3): 157–164. doi:10.1046/j.1365-3164.1997.d01-16.x. ISSN 1365-3164.
Atrophic acne scars have lost collagen from the healing response and are the most common type of acne scar (account for approximately 75% of all acne scars). They may be further classified as ice-pick scars, boxcar scars, and rolling scars. Ice-pick scars are narrow (less than 2 mm across), deep scars that extend into the dermis. Boxcar scars are round or ovoid indented scars with sharp borders and vary in size from 1.5–4 mm across. Rolling scars are wider than icepick and boxcar scars (4–5 mm across) and have a wave-like pattern of depth in the skin.
Scars (permanent): People who get acne cysts and nodules often see scars when the acne clears. You can prevent these scars. Be sure to see a dermatologist for treatment if you get acne early — between 8 and 12 years old. If someone in your family had acne cysts and nodules, you also should see a dermatologist if you get acne. Treating acne before cysts and nodules appear can prevent scars.