Atrophic acne scars are depressed pits that form when an inflamed pore ruptures and healing produces too little collagen. Dermatologists divide them into ice-pick, boxcar, and rolling scars based on width, depth, and edge shape. About 80% of people ages 11-30 get acne, and about one in five of them develops acne scars. Deep nodules, cysts, picking at breakouts, and genetics raise the risk.
Medical information disclaimer: This article is for general educational purposes only and does not provide medical advice, diagnosis, or treatment. Always consult a physician or other qualified health professional about symptoms, medications, tests, or treatment decisions.
Table of Contents
- Why does acne leave pits?
- How can you tell the three types apart?
- Which treatment fits which scar?
- What should you do before scar treatment?
Why does acne leave pits?
An inflamed pore can rupture and damage nearby skin tissue. When repair makes too little collagen, the surface heals with a depression.
This process differs from raised scars, which come from excess collagen, according to the Cleveland Clinic Cleveland Clinic's overview of acne scars. Controlling active breakouts lowers the chance of new pits. Fewer inflamed lesions means fewer ruptures that can scar.
How can you tell the three types apart?
Size, shape, and edges separate the three types. Ice-pick scars are narrow and deep, boxcar scars are broader with sharp edges, and rolling scars are wide with sloping edges.
Ice-pick scars account for an estimated 60-70% of atrophic scars, while boxcar scars make up about 15-20%, according to the Journal of Clinical Medicine review Journal of Clinical Medicine review of atrophic scar types. Rolling scars get their uneven look because fibrous bands tether the dermis to the tissue below.
- Ice-pick: narrow V-shaped tract under 2 mm wide that extends into the dermis
- Boxcar: broader round-to-oval U-shaped depression with sharply defined vertical edges
- Rolling: widest type, up to about 5 mm, with sloping edges and an undulating surface
Which treatment fits which scar?
Dermatologists match the method to the scar shape. High-concentration TCA CROSS or punch excision targets ice-pick scars, fractional laser or microneedling targets boxcar scars, and subcision releases the tethers under rolling scars, according to DermNet DermNet's guidance on TCA CROSS for acne scars.
No single treatment reliably erases atrophic scars. Complete resolution with TCA CROSS alone is unlikely, deep ice-pick scars respond least to energy devices, and most patients need combination therapy.
What should you do before scar treatment?
Treat active inflammation first and protect skin from the sun. Fewer breakouts means fewer new scars, and many scar procedures carry pigmentation risk.
That risk is higher in darker skin, so sun protection matters during and after peels, lasers, and TCA, according to the Cleveland Clinic Cleveland Clinic's advice on acne scars and sun protection. Ask a dermatologist which combination fits your scar mix, skin tone, downtime, and budget.