Atrophic acne scarring occurs when the skin loses tissue volume, resulting in depressions on the surface. Boxcar scars are a common subtype, leaving a noticeable textural irregularity. While challenging, these indentations are treatable. Modern dermatological treatments offer multiple effective pathways for improving skin texture and minimizing their appearance.
Defining the Appearance and Structure of Boxcar Scars
Boxcar scars are characterized by broad, oval, or round depressions in the skin. They are defined by sharply demarcated, vertical edges, giving them a “punched-out” or crater-like appearance. These steep sides distinguish them from other depressed scars.
The base of a boxcar scar is typically flat, resembling the shape of a boxcar, hence the name. They are generally wider than they are deep, with diameters often ranging between 1.5 to 4.0 millimeters. Shallow variants respond readily to resurfacing treatments, while deeper ones penetrate the reticular dermis, making them more resistant to superficial remedies.
The Underlying Causes and Formation of Boxcar Scars
Boxcar scars form as a direct result of inflammatory skin trauma, most commonly from severe nodular or cystic acne. Intense inflammation causes rapid destruction of underlying collagen fibers within the dermis, resulting in a net loss of tissue volume.
When the skin attempts to heal, inadequate collagen regeneration fails to provide structural support. This lack of support causes the affected area to be pulled down, creating the sunken indentation. While severe acne is the primary cause, other inflammatory conditions, such as chickenpox, can also trigger this mechanism of tissue destruction and subsequent scarring.
How Boxcar Scars Differ from Other Acne Scars
Atrophic acne scars are classified into three main types: boxcar, icepick, and rolling, differentiated by their shape, depth, and edge definition. Boxcar scars have a wide base, broad depression, and sharp, angular walls, representing a localized area of collagen loss.
In contrast, icepick scars are narrow, deep, V-shaped pits that resemble a puncture wound. They extend deep into the dermis and are much deeper than they are wide. Rolling scars present as wide, shallow depressions with sloping, undulating edges. These scars are caused by fibrous bands pulling the skin down, giving the skin a wavy, uneven texture.
Professional Treatment Options for Boxcar Scars
Treating boxcar scars often requires a multi-modal approach, as combined procedures typically yield the most comprehensive improvement. The specific treatment plan is customized based on the scar’s depth and overall skin condition.
Dermal Fillers
Dermal fillers are an effective option for shallow to moderate boxcar scars, providing an immediate lift to the depressed area. Fillers, such as hyaluronic acid-based products, are injected directly beneath the scar to restore volume and elevate the indentation to the level of the surrounding skin. Some fillers also act as collagen stimulators, encouraging the body to produce new structural support over time.
Surgical Techniques
For deeper, isolated scars, surgical techniques like punch excision or punch grafting are often employed. Punch excision involves using a small tool to completely remove the scar tissue, closing the resulting wound with fine sutures to create a smaller, less noticeable, linear scar. Punch grafting is a variation where the excised area is immediately replaced with a small piece of healthy skin, often taken from behind the ear.
Laser Resurfacing
Laser resurfacing treatments work by stimulating collagen production and remodeling the skin’s surface. Ablative lasers vaporize the top layer of skin and heat the underlying tissue, which encourages new collagen formation and smooths the sharp edges of the scars. Non-ablative fractional lasers heat the skin without removing the top layer, relying on thermal energy to promote internal collagen synthesis and skin renewal.
Collagen Induction Therapies
Microneedling, especially when combined with radiofrequency (RF) energy, is a widely used method for collagen induction. This process uses fine needles to create controlled micro-injuries in the skin, triggering the body’s natural healing response and the formation of new collagen and elastin. The addition of RF energy delivers heat deeper into the dermis, accelerating the remodeling process and improving scar texture.
TCA Cross Technique
Targeted chemical peels, such as the trichloroacetic acid (TCA) cross technique, are specifically used for treating the steep edges of boxcar scars. This method applies a high concentration of TCA directly to the base and walls of the scar, causing a controlled, localized injury. The resulting healing process stimulates collagen production from the bottom up, helping to elevate the scar and blend it with the surrounding skin.