Acne scars: why the type decides the treatment

Marks are not scars

The single most useful distinction, and the one most often missed, is between a mark and a scar.

After a spot clears, many people are left with a flat brown, purple or red patch. These are post-inflammatory hyperpigmentation and post-inflammatory erythema — pigment and blood vessel changes in skin whose surface and structure are intact. They are flat. Run a finger over them and you feel nothing. Crucially, they fade on their own over months, and fade considerably faster with sun protection and appropriate topical treatment.

A scar is a change in the skin's structure — tissue that was lost during healing, or tissue laid down in excess. Scars have texture. They catch the light differently. They do not resolve on their own, and no amount of topical treatment restores the missing structure.

This matters commercially as well as clinically: a course of resurfacing sessions sold to treat what were only pigmented marks will appear to work, because the marks were going to fade anyway.

Atrophic scars: rolling, boxcar, icepick

Most acne scarring is atrophic — depressed, because collagen was lost. It is conventionally divided into three types, and a single face usually carries a mixture of all three.

Rolling scars

Broad, shallow depressions with sloping edges, giving skin an undulating appearance most visible in raking light. They are caused by fibrous tethers pulling the skin's surface down to deeper tissue.

Boxcar scars

Round or oval depressions with sharply defined vertical walls, like a small crater. They may be shallow or deep, and are commonly seen on the cheeks and temples.

Icepick scars

Narrow, deep, V-shaped tracks that taper to a point beneath the surface. They are the most difficult to treat, because their depth is out of proportion to the tiny amount of surface they occupy.

Raised and keloid scars

Less commonly, acne heals with too much collagen rather than too little, producing a raised scar. Hypertrophic scars stay within the boundary of the original spot. Keloids grow beyond it, sometimes considerably, and are more common on the chest, shoulders, upper back and jawline, and in people with deeper skin tones or a family history of them.

These are treated in an entirely different direction from atrophic scars — the aim is to reduce and flatten tissue rather than to rebuild it. Applying a resurfacing approach intended for depressed scarring to a keloid-prone patient risks making things worse.

Why the type changes the treatment

Because the underlying problem differs, the sensible approach differs:

• Rolling scars are tethered from below, so treatment is generally aimed at releasing those tethers and stimulating collagen underneath them.
• Boxcar scars have defined walls, so approaches that resurface and soften the edges tend to be more useful.
• Icepick scars are too deep and narrow for surface resurfacing to reach, and are usually addressed with targeted techniques applied scar by scar.
• Raised and keloid scars need treatment that reduces excess tissue, and carry a genuine risk of recurrence.
• Pigmented marks need sun protection and topical treatment, and often mostly time.

In practice, most people have a combination, so a realistic plan usually combines approaches and runs over a course rather than a single session. Which combination is right for your face is a clinical decision made after examining it — which is why this article deliberately does not tell you which procedure to book.

What has to happen first

Active acne is controlled before scar treatment begins. There are two reasons. New lesions forming during a course of scar treatment create new scars alongside the ones being treated, and several resurfacing procedures are unsafe on actively inflamed skin. Getting the acne under control is part of treating the scarring, not a delay before it.

Skin type is assessed honestly. Skin with more melanin responds well to scar treatment but carries a higher risk of post-inflammatory hyperpigmentation afterwards. That risk is managed with conservative settings, test patches and strict sun protection — not by pretending it does not exist.

Expectations are agreed before money is spent. Good scar treatment produces meaningful, visible improvement. It does not restore skin to the state it was in before the acne. Anyone promising the latter is selling something.