Treating acne scars is much trickier than curing acne. This is because some scars, once formed, remain for life. Depending on the type of acne scar, the correct treatment method is chosen and the patient’s wishes are listened to.
Treat acne scars only after acne has completely healed
There is no point in treating acne scars if the skin is not free of new acne. This is because the unevenness and redness of acne scars is caused by the continuous formation of acne, and if the source is not broken, more scars will appear one after another.
External treatments such as lasers and peels are not powerful enough to stop new acne from forming. If you still have acne, please refer to ‘Acne treatment‘ and get your acne treated first.
Types of acne scars
After acne has healed, the most common type of acne scar is acne scars, which leave behind red pigmentation. Acne scar pigmentation can be brown, reddish-black or blue, as well as red.
Causes of redness
Red blood cells in the blood have a red component called haemoglobin, and haemoglobin is what makes blood appear red. Red acne scars are also caused by this haemoglobin.
When acne occurs, the inflammation damages the cells. In an attempt to heal the damaged area, capillaries in the skin dilate and new capillaries are created. Normally, as the acne heals, the capillaries gradually shrink and regress, and the redness naturally becomes less noticeable.
However, if the capillaries remain without regression, or if chronic acne (chronic inflammation) causes capillaries to grow abnormally, or if the inflammation breaks down the capillaries and red blood cells leak between skin cells, red acne scars can result.
Erythema and Purpura
Dilated and bloodshot capillaries are called ‘erythema’, while red blood cells leaking from the capillaries and turning reddish purple are called ‘purpura’.
Differences in color
Acne scar pigmentation can be red, purplish or reddish-black.
When haemoglobin (including that in blood vessels) is in the shallow layer of the epidermis or dermis (papillary layer), the spots appear red. When haemoglobin is in a slightly deeper layer of the dermis (below the subpapillary layer), the color appears reddish purple to blue to reddish black.
Also, haemoglobin is red when oxygen is bound to it (oxyhaemoglobin), but when oxidised it becomes deoxyhaemoglobin, which appears red-purple to blue to reddish-black.
Atrophic scars are depressed acne scars, which appear as small indentations in the skin.
Depending on their morphology, they are divided into ‘Ice-pick scars’ (V-shaped), ‘Rolling scars’ (M-shaped) and ‘Boxcar scars’ (U-shaped). The type with atrophied subcutaneous fat is sometimes called ‘Lipoatrophic scars’.
Usually, multiple forms of acne scars are mixed.
Ice-pick acne scars are narrow, deep depressions of less than 2 mm in diameter, as if poked with an ice pick. They account for 60-70% of atrophic scars.
The indentations reach deep into the dermis and extend almost to all layers. Histologically, the dermal layer beneath the epidermis is completely absent or almost completely missing.
Rolling acne scars are large, gentle depressions with a diameter of 5 mm or more. They account for 15~25% of atrophic scars.
They are attached to the epidermis and fascia by fibrosis tissue and are pulled together. They are also called ‘anchored acne scars’ or ‘tethered acne scars’ because the fibrotic tissue looks like a ship’s anchor.
They are distinguished by the fact that the edges are gently sloping and not right-angled as in box-shaped scars. If the indentation deepens when the facial muscles are moved, as if pulled by the muscle movement, it can be determined that it is attached to the fascia.
Boxcar acne scars are circular or oval-shaped depressions with right-angled edges. They account for 20-30% of atrophic scars.
Beneath the epidermis, the scar tissue is hardened and resembles a chicken pox scar.
Acne scars are caused by atrophy of the subcutaneous tissue (fatty tissue). The inflammation of the acne causes degeneration and scarring of the fatty tissue, which in turn causes indentation of the overlying dermis and epidermis.
Diagnosis is determined by tangential lighting and skin extension tests.
Age-related loss of fatty tissue and dermis is a contributing factor. A similar condition occurs when acne scars, which were not noticeable in youth, become more prominent as the skin loses its elasticity with age.
Hypertrophic scars and Keloids
Hypertrophic scars are acne scars that have become raised, as opposed to atrophic scars. It has been suggested that the two are a continuum of conditions, although those that are more inflamed, reddened and tending to enlarge are called keloids to distinguish them.
The predilection for the area is for areas where the skin is easily stretched, such as the anterior chest, shoulders and lower abdomen. In acne scars, hypertrophic scars are found on the chest, shoulders and jaw.