Boxcar scar treatment

Picture of By Ulrik knap, md, laser & acne scar specialist

By Ulrik knap, md, laser & acne scar specialist

Treating acne scars is a medical art that requires great skills and the use of the right methods. Not one method fits all acne scar types. Hence, I treat acne scars with different methods and choose the best methods for each individual acne scar. Combining different methods – when relevant – is the only way to achieve the highest cure rate. Therefore, patients come from most of the world to visit my office and have their acne scars treated by me personally.

Identifying the right scar type

Identifying the right acne scar type is one of the most important steps when planning an acne scar revision program for one of my patients. Matching the right acne scar type with the right methods is simply the way to go for good results. The same applies for boxcar scars.

acne scars - treatment - dr Knap

What causes Boxcar scars?

Boxcar scars are a so-called atrophic acne scar, which means that the scar has some degree of tissue loss.

You probably wouldn’t be too surprised when I say that acne scars are caused by acne! However, have you ever thought of why some people get acne scarring while others don’t?

This all depends on genetics and the way the skin manages to repair itself after the acne-related inflammation.

During the repairing process, the body’s own defense system plays an important role in rebuilding the skin and removing all the tissue which was destroyed by acne.

However, in patients who are prone to develop atrophic acne scarring, there is a too large removal of old tissue compared to the amount of tissue that is rebuilt. The consequence is that atrophic scarring develops with depression in the skin. If you want to learn more about the pathogenesis, please read the article “What causes acne and acne scarring”.

Different kinds of acne scars might develop during this repairing process where boxcar scars are one of them, being round to oval depressions with sharply demarcated vertical edges, similar to varicella (chickenpox) scars. 

They are clinically wider at the surface than ice pick scars and do not taper to a point at the base.

How common are Boxcar scars?

Boxcar scars are seen in roughly 20%–30% of all patients with atrophic acne scars. This makes it the 2nd most common form of acne scars with ice pick scars being the most common and rolling scars being the third most common acne scar type.

Patient with a combination of box scars and ice pick scars. Box scars are the second most common form of atrophic acne scars.

Dr. Knap about how to get rid of Boxcar scars

The first step to achieve a high cure rate of boxcar scars is to make a thorough physical examination to identify the different acne scar types of the patient. This involves a good look at the skin and examination of the acne scars with indirect lighting to see the shadows of the scars, touching the skin to identify any deeper-lying fibrosis and to see the patient mimic and smile to identify any tethered acne scars that should be managed with subcision.

Identifying the scar type of each individual acne scar is vital since this form the whole foundation for the planning and execution of a profound acne scar revision program matching the right techniques with the right acne scar type. On the contrary, treating all acne scar types the same, won’t give the highest cure rate.

Just to give some examples, my experience is that particularly shallow boxcar scars respond very well to treatment with a fractional CO2 laser, while deep boxcar scars might be better treated with techniques such as TCA cross or punch excision.

Chickenpox scars which are another kind of boxcar scars might, on the other hand, respond very well to dermal filling (or TCA cross based on an individual examination of the skin scars).

Hence, when the boxcar scars have been identified and mapped, it’s time for the treatment. And as you might already have realized, I use different methods for different types of acne scars to achieve the highest possible cure rate for my patients.

How to get rid of Boxcar scars using a fractional laser?

The 10,600 nm fractional CO2 laser is no doubt one of the best lasers to treat shallow boxcar scars. In skilled hands, the laser can be used in ethnic skin types as well.

The fractional CO2 laser produces small columns of ablation or coagulation in the skin, leaving the surrounding skin intact. The light from the laser penetrated the upper part of the skin and reaches all the way down to the dermis, where it causes dermal damages which stimulates new collagen creation and remodeling of the scars.

Types of acne scarring: ice pick, rolling and boxcar (shallow and deep). The thick horizontal line is the reach of ablation of CO2 laser. Rolling scars are tethered by fibrous bands to the underlying muscle fascia (SMAS).

Secondly, the fractional mode ensures fast recovery after the laser treatment.

The treatment is performed in local anesthetics, so any pain is reduced to a minimum. 

After the treatment, the skin appears red and might also appear swollen. The edema quickly subsides within 2-3 days while the redness typically lasts for a few weeks, which can be covered using a recovery makeup (e.g. Lycogel) or similar products.

The fractional laser treatment should typically be repeated 2-4 times every 4-8 weeks to achieve the best cosmetic outcome. Each time, the laser treatment causes further remodeling and improvement of the acne scars.

acne scars - before after treatment - dr Knap

Laser treatment can be combined with other techniques such as TCA cross, subcision, and punch excision as well. This can be done either in the same session or some weeks later.

Which methods I use to improve acne scars, depend on the acne scar type, the severity of the scars, and the skin type of the patient. This is based on a thorough 3-dimensional examination of the acne scars having the patient placed in a good chain in front of me and with good lighting. Learn more about fractional laser treatment of acne scars.

How to get rid of Boxcar scars using TCA cross?

TCA cross stands for TriChloroacetic Acid Chemical reconstitution of Skin Scars. This is a simple but very effective treatment that is suitable for treating deep atrophic scars in the skin caused by acne.

In selected boxcar scars, TCA cross can drastically improve the appearance of the scar. That would typically concern boxcars that for some reason are unsuited for punch excision, and where scar revision with fractional lasers wouldn’t be the optimal treatment of choice either.

TCA cross is performed by applying a tiny droplet of TCA at the bottom of each scar. This causes a local tissue damage, which breaks down the scar tissue, denatures the collagen and stimulates the tissue to start remodeling.

The delivery system can be as simple as a toothpick which has been dipped into a jar of TCA. Thereafter the tip of the toothpick is carefully placed into the scar. This is a safe and effective method.

Learn more about TCA cross.

How to get rid of Boxcar scars with punch excision?

Punch excision is a small surgical procedure local anesthetic where the acne scar is excided with a knife. Thereafter the wound is closed with sutures. This leaves a much less visible surgical scar which can markedly be improved with a fractionated laser 3-4 weeks after the surgery.

I use this technique for severe boxcar scars to achieve an immediate result before moving on to fractional laser resurfacing in an acne scar revision program.

Before acne scar revision with punch excision and TCA cross.
After punch excision and TCA cross

The advances of punch excision are that you get an immediate result and get a much less visible surgical scar. However, punch excision should always be followed by treatment with fractional laser to improve the cosmetic outcome of the surgical scar as well as the overall skin texture.

How to get rid of chickenpox scars?

Skin and scar examination is essential in each individual case, and not all boxcar scars are the same. For instance, in chickenpox scars, both location, skin color, the thickness of the skin, depth of the scars as well as scar site matters when choosing the optimal treatment.

In some cases, particularly in shallow chickenpox scars in the temples, where the skin is thin, good results can be achieved by performing superficial subcision with a fine needle and dermal filling. Great care should be taken in this area due to the close proximity to blood vessels. Hence, this treatment should only be done by an expert who knows his anatomy.   

When performing dermal filling of chickenpox scars, I inject a droplet of filler in the dermis to replace the volume loss of the scar. Using this technique, I can treat multiple chickenpox scars during a session, and the result is immediate.

Since the treatment is combined with careful subcision, the result is long-lasting.

Dr. Ulrik Knap about treating boxcar scars

Identifying the right acne scar type and subtype is essential when treating boxcar scars to achieve a high cure rate. I do this with the patient sitting in a good chair in front of me using indirect lighting, touching the skin and having the patient mimic and smile. 

By performing my initial acne scar examination, I find that most patients have a mixture of acne scar types, which each have to be treated differently using a variety of techniques, including TCA cross, subcision, dermal fillers, punch excision, minor surgery, and laser resurfacing.

Matching the acne scar type with the right methods is one of the reasons for my high success rate.

When I have identified the right acne scar types, the scars are mapped and photographed. Thereafter I construct an acne scar revision program that is specifically tailored for the patient and his or her acne scars.

Best Regards

Ulrik Knap, MD., Laser & Acne scar specialist

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