What Are Acne Scars and How Are They Treated?

Acne Scars: Why "Classifying the Scar Type" Comes Before Treatment

Acne vulgaris is one of the most common chronic inflammatory skin conditions — roughly 85% of adolescents experience acne at some point. While the inflammation of acne can resolve, it often leaves behind **acne scars**, a long-term issue affecting both appearance and mental health. Research links acne scarring to reduced confidence, poorer self-image, social avoidance, and lower quality of life — meaning scar treatment isn't purely cosmetic, but part of restoring a patient's overall quality of life.

1.How Acne Scars Form

Acne scars don't result from inflammation alone — they stem from aberrant wound healing, involving three key mechanisms:

1. Matrix metalloproteinase (MMP) imbalance. Inflammatory cytokines during active acne raise MMP-1, MMP-3, and MMP-9, which break down type I and III collagen, elastin, and the basement membrane. When this process is excessive, fibroblasts can't rebuild tissue fast enough, leading to permanent tissue loss — an atrophic scar.
2. Reduced tissue inhibitors of metalloproteinases (TIMPs). TIMPs normally restrain MMP activity, but in patients who develop scarring, elevated MMP often coincides with reduced TIMP — tipping the balance toward ECM breakdown over rebuilding, causing the skin to sink.
3. Disrupted TGF-β1 signaling. TGF-β1 is one of the most important growth factors in wound healing, driving fibroblast activity, collagen production, and tissue remodeling. When this signaling is disrupted, skin can't fully repair itself, leaving a permanent scar.

2.Types of Acne Scars

• Atrophic scars are the most common type, accounting for roughly 75–90% of cases, and are divided into three subtypes:
• Ice pick scars (~60–70% of scars): small, narrow openings that are very deep — under 2mm in diameter, V-shaped, often reaching the reticular dermis or even subcutaneous fat, which is why they respond poorly to superficial treatments.
• Boxcar scars (~20–30%): wide openings with sharp edges and flat bases, U-shaped or square, roughly 0.1–0.5mm deep.
• Rolling scars (~15–25%): wide, sloped, wave-like depressions caused by fibrous tethers pulling the skin downward.

Clinical pearl: Acne scars shouldn't all be treated with one method. Ice pick, boxcar, and rolling scars respond differently to treatment, so classifying the scar type always comes first, followed by selecting the appropriate technique — an approach known as morphology-driven treatment, the current standard of care.

3.Treatment Approach: Matched to Scar Type, Not One-Size-Fits-All

Once scar type is identified, the main treatment options include:

• Subcision — best for rolling scars with fibrous tethers, releasing the tethering tissue beneath the skin with a needle.
• Fractional laser — stimulates new collagen through controlled injury; suited to shallow-to-moderate boxcar and rolling scars.
• RF microneedling — drives deeper dermal remodeling than superficial fractional laser; useful across multiple scar types.
• TCA CROSS — a technique specific to ice pick scars, applying concentrated TCA precisely into the narrow, deep opening to stimulate collagen formation.
• Biostimulators or fillers — add volume beneath scars once they've been shallowed, or in scars where tissue volume loss is prominent, chosen based on scar characteristics.
• PN (Polynucleotide) plays a role as an adjunct treatment, helping improve skin quality and create a regenerative environment around scarred skin — but shouldn't be used as a standalone primary treatment, since its mechanism doesn't directly address the root causes of scarring (like releasing fibrous tethers or driving deep remodeling the way subcision or fractional laser does).

In practice, most patients need a combination of techniques matched to the type and severity of their scarring, planned individually — there's no single formula that works for everyone.

4.Conclusion

Acne scars result from disrupted wound healing at the MMP, TIMP, and TGF-β1 level — not inflammation alone. Effective treatment always starts with correctly classifying the scar type, since ice pick, boxcar, and rolling scars respond differently. Core treatment options include subcision, fractional laser, RF microneedling, TCA CROSS, and biostimulators/fillers as appropriate, with PN serving as a skin-quality adjunct rather than a primary treatment.