Acne scars are a common complication of acne and have various types and severity. Not only are acne scars a physical issue, but it can also cause a variety of emotional, psychological, and social implications.

Acne scars are a response to inflammation and tissue damage during the acne lesion healing process. The severity and type of acne scars can depend on various factors, including genetics, the depth and duration of the acne lesions, and the individual’s skin type and healing process. In some cases, the body’s response to the inflammation caused by acne lesions can lead to an overproduction or reduction of collagen. Too much collagen can result in raised scars, such as hypertrophic scars or keloid scars, while too little collagen can result in depressed scars. Applying pressure on an inflamed acne lesion can promote pus to spread wider into the surrounding skin causing more damage. (See below image)

Acne scars can be classified in different groups.

1. Discolored scars: (Can be combined with a depressed or hypertrophic scar.)
   1. Red/Purple: commonly the first stage after an inflammatory acne lesion has healed. Also known as Post Inflammatory Erythema (PIE)
      
   2. Brown: some PIE lesions may develop into brown-coloured lesions which is due to the formation of melanin. Also known as Post Inflammatory Hyperpigmentation (PIH)
      
2. Depressed (sunken) scars
   
   1. Ice-pick scars: deep, narrow scars that resemble small puncture wounds.
      
   2. Boxcar scars: broader than icepick scars, flat with sharp, angled edges.
      
   3. Rolling scars: wider scars with sloping edges.
      
   4. Atrophic scars: deeper scars with sloping edges, usually larger than other depressed scars
      
3. Elevated (raised) scars
   1. Hypertrophic scars: caused by the excess production of collagen during the healing process.
   2. Keloid scars: thick and extend beyond the boundaries of the acne lesion.

Treatment options for acne scars depend on the type and severity of scarring, as well as the patient’s skin type and medical history. If there is a combination of scar types, multiple modalities may be required. Multiple sessions are commonly required for improvement and complete “cure(resolution)” of depressed/elevated scars is very rare.

1. Discolored scars:
   1. PIE: certain lasers with specific wavelength to target the blood and blood vessels contributing to the red color of the lesion
   2. PIH: similar to hyperpigmentation treatments (see here-link to hyperpigmentation page)
2. Depressed scars:
   1. Laser resurfacing: fractional type lasers to stimulate collagen
   2. Microneedle Radiofrequency (RF) to stimulate collagen ▪ These treatments commonly require topical anesthesia and have downtime involved in the recovery process.
3. Rolling/Atrophic scars
   1. Same as other depressed scars (see 2.)
   2. Dermal fillers: can be injected under certain rolling/atrophic scars to raise the lesion closer to the surrounding skin level. The results may be temporary. These include hyaluronic acid, polynucleotides.
4. Hypertrophic scars
   1. Topical steroids
   2. Steroid injections
   3. Silicone sheets/gel
   4. Laser
   5. Surgery
5. Keloid scars:
   1. Same as for hypertrophic scars (see 4.)
   2. Other: 5-Fluorouracil (5-FU), Imiquimod, Verapamil injections
6. Minor Surgery: In some severe cases, a surgical procedure such as a punch excision may be necessary to remove deep scars. For rolling/atrophic scars which have tethered bands, subcision using a special needle may help raise the level of the scar.

Since acne scars are difficult to treat and can cause detrimental effects on the patient, early and proper treatment of acne in addition to avoiding recurrence to prevent scars is of critical importance. If acne scars develop, with proper treatment, the appearance of acne scars can be improved. However, as mentioned above, most acne scars cannot be completely eliminated (unless surgically removed in cases of certain depressed scars), Therefore it is important to have proper expectations and understanding of treatment benefits and risks involved.