Atrophic Acne Scar Treatment: A Pathophysiology (Rolling scars, Boxcar scars, Ice-pick scars)-Based Care Map (Classic subcision, MINI subcision, Fractional CO₂ / Er:YAG, RF microneedling, TCA CROSS)
- Mayta
- 21 hours ago
- 4 min read
Core principle
Atrophic acne scars = loss of collagen + abnormal dermal remodeling.But the dominant mechanism differs by scar type, so the “first move” must match the mechanism. (Canadian Board of Aesthetic Medicine)
1) Scar pathophysiology → “First-line” mechanism match
A) Rolling scars
Pathophysiology: broad depressions caused by fibrotic bands tethering dermis to deeper tissue (“tethering”).Implication: if you only do collagen stimulation (laser/RF) while tethering remains, improvement is limited. (JAAD)
✅ Primary correction = mechanical release (subcision)
B) Boxcar scars
Pathophysiology: sharply edged depressions; may be tethered (deep boxcar) and/or mainly surface/dermal loss (shallow boxcar). (Canadian Board of Aesthetic Medicine)
✅ If tethered/deep → subcision (release) ± lift/volume✅ If shallow → resurfacing (fractional laser/RF) often dominates
C) Ice-pick scars
Pathophysiology: narrow, deep “V” scars extending into deep dermis. Tethering is not the main issue. (Canadian Board of Aesthetic Medicine)
✅ Primary correction = focal chemical/surgical remodeling (TCA CROSS / punch)(Subcision is usually not the main tool here.) (DermNet®)
2) Treatment selection “Care Map” (stepwise algorithm)
Step 1 — Candidate readiness criteria (before any procedure)
Proceed only if:
Active acne is controlled (otherwise you keep creating new scars). (UpToDate)
No active infection (HSV, impetigo), no uncontrolled dermatitis
No strong history of hypertrophic/keloid scarring (relative contraindication for aggressive procedures)
Realistic expectations: improvement, not “100% erase”. (UpToDate)
Step 2 — Decide: Classic subcision vs Mini subcision
Think PLANE vs POINT.
✅ Choose Classic Subcision (plane release)
Pathophysiology match: wide tethering / rolling fields. (JAAD)Criteria
Rolling scars covering an area (cheek field looks “wavy”)
Multiple scars “blend together”
Depressions that do not lift well with skin stretch (suggests multi-band tethering)
Tool options (modern)
Nokor / large-gauge needle (strong release)
Cannula subcision (wide areas, often less bruising; technique-dependent)
Why this first: it frees the entire tethered plane—foundation for later collagen remodeling. (JAAD)
✅ Choose Mini-Subcision (point release / finishing tool)
Criteria
Isolated tethered scars (one or a few “anchors”)
Residual dimples after classic subcision
Small, focal boxcar scars with tethering
Why: it targets focal bands precisely; it’s less efficient for broad rolling fields.
Step 3 — Energy-based remodeling (after release)
Energy devices mainly induce collagen remodeling, not tether release. (UpToDate)
A) RF Microneedling (FMRF / FRM)
Mechanism: controlled dermal thermal injury + micro-needling → collagen remodeling; generally favorable safety profile, including skin of color. (Taylor & Francis Online)Criteria
Mixed rolling/boxcar scars (post-release)
Patient prioritizes less downtime
Fitzpatrick III–VI where PIH risk with ablative lasers is higher
B) Fractional Ablative Laser (CO₂ / Er:YAG)
Mechanism: fractional ablation + heat → stronger remodeling (more downtime/PIH risk). (Wiley Online Library)Criteria
Boxcar scars + texture irregularity
Thicker skin, patient can accept downtime
Often best in Fitzpatrick I–III, or carefully selected IV with conservative parameters and strong PIH prevention plan
C) Fractional Non-ablative Laser (NAFL)
Mechanism: dermal heating without removing epidermis → safer, less downtime, less dramatic per session. (UpToDate)Criteria
Mild–moderate scarring
High PIH concern / downtime limitation
Maintenance after major corrections
Step 4 — Ice-pick scar pathway (separate lane)
TCA CROSS
Mechanism: focal high-strength TCA induces controlled chemical injury → collagen remodeling within narrow pits. (DermNet®)Criteria
True ice-pick scars (narrow, deep)
Often done in sessions; concentration (70–100%) chosen by clinician based on risk/benefit and skin type (Springer)
Important safety nuance (criteria)
Higher PIH risk in darker skin types; technique and aftercare matter (even TCA CROSS can occasionally worsen scars if poorly delivered). (JCAD)
3) “Which skin type gets what?” (practical decision grid)
Fitzpatrick I–III
Rolling: Classic subcision → (AFL CO₂/Er:YAG or RF MN)
Boxcar: AFL works very well; NAFL if downtime-limited (Wiley Online Library)
Ice-pick: TCA CROSS (with standard PIH precautions)
Fitzpatrick IV–VI (many Thai patients are III–V)
Rolling: Classic subcision first (key) (JAAD)
Remodeling: RF microneedling often preferred for pigment safety (Taylor & Francis Online)
If using ablative fractional laser: lower density/energy + rigorous pigment prevention plan (clinician-specific) (Wiley Online Library)
Ice-pick: CROSS is effective but requires careful technique and aftercare; counsel PIH risk (DermNet®)
4) Sequencing and “criteria” for combining (what to do first)
A commonly effective sequence for mixed scars (rolling + boxcar ± ice-pick) is:
Why this order (pathophysiology):
Release first, otherwise collagen remodeling happens on a tethered base. (JAAD)
5) Practical “criteria checklist” per intervention
Classic subcision — choose it when:
✅ Rolling scars dominate ✅ Field tethering (area problem) ✅ Stretch test: depressions don’t fully lift ❌ Avoid/very cautious if: bleeding disorder/anticoagulation issues, strong keloid tendency (relative)
Mini subcision — choose it when:
✅ Isolated scars or residual anchors post-classic ✅ “One stubborn dimple” pattern ❌ Not ideal as first-line for rolling fields (low efficiency)
Fractional CO₂ / Er:YAG — choose it when:
✅ Texture irregularity + boxcar component ✅ Patient accepts downtime ✅ Lower PIH risk skin type or conservative plan (Wiley Online Library)
RF microneedling — choose it when:
✅ Mixed scars; wants less downtime ✅ Fitzpatrick III–VI / pigment concern (Taylor & Francis Online)
TCA CROSS — choose it when:
✅ True ice-pick scars
✅ Patient understands PIH risk + needs multiple sessions (DermNet®)
6) What “VL laser” can/can’t do (criteria)
If by “VL” you mean vascular laser (PDL/KTP): ✅ Helps redness / post-acne erythema ❌ Does not correct tethering or scar depth meaningfully
So it’s an adjunct, not a core scar-depth tool.
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