Boxcar scars are a common consequence of severe acne, representing a type of atrophic or depressed scar left behind after intense skin inflammation subsides. They are a significant texture concern, making the skin appear uneven and pitted. Understanding the characteristics, formation mechanism, and specialized treatments available is the first step toward improving skin texture. This overview details the nature of boxcar scars and the professional interventions used to smooth their appearance.
Defining and Identifying Boxcar Scars
Boxcar scars are distinct depressions characterized by a round or oval shape and a wide base. They are named for their similarity to a train boxcar, featuring steep, sharply defined vertical edges that drop down to a flat base. This appearance distinguishes them from other acne scars, such as the narrow “icepick” scars or the wave-like “rolling” scars that have sloping edges.
The well-defined borders of a boxcar scar create an abrupt transition from the surrounding healthy skin to the scar tissue, making the depression noticeable. They typically present as shallow to moderate indentations, most often found on thicker skin areas like the temples and cheeks. Deeper versions can extend into the reticular dermis, making them more challenging to elevate and blend with the surrounding skin.
Causes and Formation
The development of a boxcar scar is rooted in the destructive process of severe inflammatory acne, particularly nodular or cystic lesions. When these deep breakouts occur, the intense immune response causes widespread damage to the underlying skin tissue. This inflammation destroys the collagen fibers and subcutaneous fat that normally support the skin’s structure.
As the acne lesion begins to heal, the skin often fails to produce sufficient new collagen to replace the lost tissue. This inadequate healing response results in a localized absence of dermal support, causing the surface skin to collapse inward and form a depression. The surrounding healthy tissue heals and pulls taut, creating the characteristic sharp, vertical walls that define the boxcar shape.
Professional Treatment Options
Treatment for boxcar scars focuses on two goals: physically elevating the depressed floor of the scar and stimulating new collagen production to remodel the scar tissue. Because boxcar scars involve tissue loss and sharp edges, a multi-modal approach is recommended for optimal results.
Subcision is a mechanical technique used to treat deeper boxcar scars, especially when the scar is tethered to the underlying tissue. A fine needle or cannula is inserted beneath the skin and moved in a fanning motion to sever the fibrous bands that pull the scar floor downward. Releasing these tethers allows the scar to rise and encourages the formation of new collagen and elastin fibers.
Dermal fillers, such as hyaluronic acid or poly-L-lactic acid, are injected after subcision or as a standalone treatment for shallow scars. These substances add immediate volume to the depression, temporarily lifting the scar base to be flush with the surrounding skin. Certain fillers also act as collagen stimulators, promoting long-term improvement after the initial product is absorbed.
Laser resurfacing treatments, including both ablative (like CO2 or Erbium) and non-ablative fractional lasers, refine the scar’s appearance. Ablative lasers vaporize microscopic columns of tissue, smoothing the harsh vertical walls and triggering a wound-healing response that generates new collagen. Non-ablative lasers work deeper without removing the surface skin, stimulating dermal remodeling with less downtime.
For narrow or smaller boxcar scars, the Trichloroacetic Acid Chemical Reconstruction of Skin Scars (TCA CROSS) technique provides precise chemical resurfacing. A high concentration of TCA (often 70% to 100%) is applied directly into the scar pit using a fine applicator. This controlled chemical injury causes the scar tissue to frost and then peel, stimulating collagen production from the base upwards to elevate the depression and reduce its defined edges.
Prevention Strategies
Proactive management of severe acne is the most effective defense against the formation of boxcar scars. Early and aggressive treatment of inflammatory lesions, such as cystic or nodular acne, minimizes the duration and intensity of the inflammation that causes deep tissue destruction. Avoiding picking, squeezing, or manipulation of active pimples is also a direct preventative measure. Such actions exacerbate inflammation, increase trauma, and raise the likelihood of permanent scarring.