Brown is melanin, red is vessels, dents are lost collagen, raised is excess. Four types, four fixes.
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Wi Young-jin · Chief director
Seoul National University College of Medicine · Seoul National University Hospital Specialist
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Understanding Acne — 1.1 Folliculitis vs Acne
The Turning Point for Scarring — 2.1 Scar Risk by Size and Type
How to Stop It Now — 3.1 The Importance of Drainage · 3.2 Understanding Cortisone Injections Correctly
Even after acne subsides, marks are often left behind. However, the umbrella term "acne marks" actually encompasses four distinct issues: brown marks, red marks, indented scars, and raised scars. While it might seem like a single medication could treat them all, each of these four types has a different underlying mechanism, meaning the treatments are also completely different. Using the wrong product on one type for too long means losing precious time to properly treat another.
Even after acne subsides, marks are often left behind. However, the umbrella term "acne marks" actually encompasses four distinct issues: brown marks, red marks, indented scars, and raised scars. While it might seem like a single medication could treat them all, each of these four types has a different underlying mechanism, meaning the treatments are also completely different. Using the wrong product on one type for too long means losing precious time to properly treat another.
First, You Need to Identify Your Type of Acne Mark
Here are the four categories. PIH* refers to "brown" marks left by leftover melanin. PIE* refers to "red" marks left by lingering blood vessels. Atrophic scars are "indented" areas caused by a lack of dermal collagen. Hypertrophic scars are "raised" areas where collagen has overgrown.
Take a close look in the mirror at the color and texture of your marks. If it is flat and brown, it is PIH; if it is flat and red, it is PIE; if you gently run a finger over it and feel a slight dip, it is atrophic; and if it is puffy and raised, it is hypertrophic.
* PIH (Post-inflammatory Hyperpigmentation): A state in which excess melanin remains at the site of inflammation, appearing as brown or dark marks. The recovery speed depends on whether the melanin is located in the epidermis or the dermis.
* PIE (Post-inflammatory Erythema): A state in which tiny blood vessels in the dermis, dilated during inflammation, fail to subside and remain. They appear red and characteristically fade briefly when gentle pressure is applied before filling back up with color.

Brown Marks (PIH) are a Battle Against UV Rays
The melanin in PIH darkens even more when exposed to UV rays. Therefore, your number one treatment priority is "sun protection." Apply sunscreen of SPF 30 or higher every single day, at least on the affected spots. Without this step, no brightening treatment will show real progress.
The next line of defense includes toning (low-intensity laser), topical tretinoin, and antioxidants like Vitamin C. In many cases, these marks fade within 3 to 12 months. Deep dermal melanin that has penetrated into the dermis takes longer and requires the help of devices like IPL or Picosecond lasers.

Red Marks (PIE) are Lingering Blood Vessels
PIE is about "blood vessels," not melanin. Because of this, brightening creams and pigment treatments like tretinoin have almost no effect. The answer lies in lasers that target blood vessels. Devices such as IPL, V-beam, and PDL (pulsed dye laser) coagulate the dilated blood vessels to take the redness away.
While natural recovery is possible, it is slower than PIH, typically taking 6 to 18 months. If the marks do not fade after 6 months, even just one or two vascular laser sessions can visibly lighten them. If you confuse PIH with PIE, you might end up applying brightening creams for 6 months with no results, leading to frustration.

Indented Scars (Atrophic) Require Collagen Reconstruction
Atrophic scars occur where dermal collagen has been damaged and has failed to recover. They are divided into three shapes. Even within a single session, we combine different devices tailored to each shape. In my clinical experience, a combination of a CO2 laser to control depth on a dot-by-dot basis combined with CureJet to tidy up the inner dermis delivers the most natural results.
An ice-pick scar* is a narrow and deep puncture-like mark, which responds well to a CO2 laser targeting individual dots. Boxcar scars have sharp edges, so the same CO2 laser is used to smooth out the transition of the borders. Rolling scars have wide, gentle slopes, making CureJet ideal as it breaks the fibrous bands underneath the dermis. Since these are permanent structural changes, they will not disappear in a single session, but building up consistent treatments over about a year often leads to a 50% to 80% improvement.
* Ice-pick scar: A narrow, deep, pinpoint-like atrophic scar. Because of its depth, superficial lasers are less effective, making spot treatments like TCA CROSS (high-concentration TCA reconstruction) or punch excision more successful.

Raised Scars (Hypertrophic & Keloid): Flattening is Key
Hypertrophic scars and keloids are areas where "too much" collagen has grown. This is the exact opposite issue of atrophic scars, so the solution is to "flatten" rather than
Frequently asked questions
Q. I've been applying whitening cream to my brown spots for 6 months, but they won't fade. Why is that?
A. It is highly likely to be one of two reasons. First, the mark is actually PIE (post-inflammatory erythema, or red marks) but you have been trying to treat it with whitening agents. Second, the melanin has penetrated deep into the dermis, rendering topical treatments ineffective. Taking a closer look at the color in the mirror or getting a clinical diagnosis will prevent you from wasting any more time.
Q. Will depressed scars naturally fill in over time?
A. They rarely fill up on their own. Atrophic scars are areas where dermal collagen has been lost, so they tend to remain the same even with time. However, if you consistently undergo active treatments for about a year, the appearance and depth often show noticeable improvement. The earlier you start, the better.
Q. Are there specific areas where keloids are more likely to form?
A. The shoulders, center of the chest, upper back, and earlobes are the most common areas for these to develop. If you feel a nodule or cyst in these spots, getting a triamcinolone injection right away is the crucial first step to preventing keloids. Trying to treat them after the scars have already enlarged will require many more sessions.
Q. Why isn't my red acne mark (PIE) fading even after applying whitening products?
A. Red spots (PIE) are actually leftover blood vessels, not melanin, so whitening products won't be very effective. Targeted vascular lasers like IPL or Vbeam are the best solution.

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