Hypertrophic scars, keloids, striae, erythematous , atrophic and
pigmented scars can be treated with different types of laser
treatments available. Not every laser treatment works for each type of scar. In this review, the scar categories will be discussed along with appropriate modes of laser treatment
Hypertrophic scars and keloids affect approximately 4.5% to 16% of the general population. They usually develop within the first couple of months after surgery or trauma. The most common locations for these types of scars are the anterior chest, back, shoulders, earlobes, lower face, and generally
any pressure- or movement-dependent areas of the body. Abnormal scar formation is most common in darker-skinned patients and usually in individuals between the ages of 10 to 30
Hypertrophic scars are confined to the area of original epithelial damage. Keloids extend beyond the boundaries of the initial trauma, and can become quite large and nodular. Hypertrophic scars also usually regress and flatten over time whereas keloids may either persist indefinitely or continue to
enlarge. Both scar types may be very similar in clinical appearance, and their initial presentation may overlap considerably.
Types of Scars
There are six different categories of scars based upon clinical
appearance including hyperdrophic scars, keloids, erythematous scars, atrophic scars, pigmented scars, and striae. Clinical differentiation between scar types, while difficult at times, is necessary to ensure that the most effective treatment is chosen.
Hypertrophic scars usually develop within the first 4-8 weeks following incisional surgery or trauma. Almost all surgical or injured sites develop a variable degree of tissue hypertrophy and clinically appear as pink, firm, raised bands within the boundaries of the tissue insult. In some patients these
scars gradually disappear, whereas in others they persist or enlarge slightly. Up to 1/3 of the patients additionally complain of pruritus and dysesthesia (burning) associated with these scars. The mechanism of development of hypertrophic scars is likely related to an excessive production of collagen during the wound remodeling phase.
Hypertrophic Burn Scars Pre-Surgery
Keloids have many features in common with hypertrophic scars; both being characterized by unrestrained growth of fibrous tissue occurring after cutaneous trauma. The primary difference between the two is that keloids grow beyond the confines of the initial site of trauma and continue to grow without propensity for spontaneous regression over time. Keloids are more common on dark-skinned individuals and often present as purple-red papules or nodules on the chest, back, earlobes and posterior neck. Keloids are difficult to treat and have a very high rate of recurrence following traditional excisional methods.
After cutaneous wounding, all scars are initially erythematous due to neovascularization (new blood vessel formation) that occurs during the repair process. When erythema persists for an extended period (greater than 12 months), then it is most likely a permanent sequela and will require laser treatment for removal.
Hypertrophic Burn Scars Post-Surgery
Atrophic scars may be difficult to eradicate completely. They commonly occur after an acute varicella (chicken pox) infection or moderate to severe cystic acne. The inflammation associated with these disorders disrupts the normal underlying collagen and leaves the cutaneous surface with multiple, small indentations. Atrophic scars are initially erythematous and become increasingly hypopigmented and more fibrotic with time; occurring
commonly on the face, chest, and upper back. Traditional methods of scar revision including dermabrasion, excision, or punch grafting have shown varied results, being less precise than laser resurfacing and often associated with intensified scarring or permanent pigmentary alteration.
Pigmented scars are a consequence of epidermal injury and are more common in individuals with either olive or brown skin tones. The hyperpigmentation may either be a postinflammatory phenomenon or may be due to disruption of the dermal-epidermal junction with leakage of pigment-containing cells into the dermis. While hyperpigmentation often fades with time , it rarely returns to the pre-injury skin color and, consequently, there is usually some degree of remaining pigmentary disturbance.
Burn Scars on the Cheeks Pre-Surgery
Striae (commonly referred to as "stretch marks") appear most commonly on the abdomen, and hips after pregnancy or around the knee and shoulder joints as a result of a pubertal growth spurts. They present clinically as pink, red, or lavendar linear bands of wrinkled skin, while older striae are light in color and more fibrotic. Historically, striae are very similar to scars, with increasing fibrosis as the lesions age.
Laser Treatment of Scars
The laser of choice for treating hypertrophic scars is the 585nm pulsed dye laser. This laser was initially used to eliminate persistent erythema caused by hypervascularity in scars. Treatment with this laser, however, also results in the added benefits of improved scar pliability, smoother skin texture, and decreased bulk of scar tissue.
Burn Scars on the Cheeks Post-Surgery
With each laser session, scars are treated with the laser parameters based upon the color, thickness, and location of the scar. The entire scar is treated with the laser during each session and the patients are warned of the development of post-treatment bruising that can last for 1 week. No blistering, bleeding, or crusting should be noted. After and between each laser treatment, the patient should protect the skin from sun exposure.
It is typical to see 50% or greater improvement in scars after 2 treatment sessions. Treatments are continued at 6 to 8 week intervals to eliminate any erythema or hypertrophy.
Similar to hypertrophic scars, keloids are best treated with the 585nm pulse dye laser. Additional treatment sessions are often required to obtain significant improvement. The biggest side effect associated with treatment of these scars is pigmentary alteration (hyperpigmentation or hypopigmentation), which usually subsides over time.
The 585nm pulse dye laser is also appropriate for erythematous scars. Clinical results are typically excellent with marked scar fading noted within one or two sessions.
Burn Scars on the Face Pre-Surgery
Successful treatment of mild to moderately severe atrophic scars has been achieved with high energy pulsed or scanned carbon dioxide (CO2) and erbium: YAG lasers. These laser systems vaporize the involved skin surface and heat a limited amount of superficial dermal tissue, providing overall improvement of skin contour. The CO2 laser is particularly effective at inducing new collagen formation and remodeling, due to its controlled delivery of energy and subsequent limited residual thermal damage. The CO2 and erbium lasers are ideally suited for moderate to severely atrophic scars, with relatively low incidence of postoperative complications. These laser systems represent a major advance in cutaneous resurfacing and have significantly improved our ability to ameliorate atrophic scarring.
Treatment for these types of scars requires a pigment-specific laser in order to lighten unwanted scar darkening. A number of pigment-specific systems are available for use, including q-switched ruby, alexandrite, and Nd:YAG lasers. Immediately, after treatments, the scars turn ash-white followed by crusting, and eventual pigment fading.
Striae (stretch marks)
Treatment of striae is notoriously difficult. Some improvement in younger, more erthematous (pink or lavender) striae can be expected with a 585nm pulsed dye laser. Reduced discoloration and improved skin texture can be seen within one or two treatments.
Burn Scars on the Face Post-Surgery
Laser surgery is now considered the preferred mode of treatment for a variety of scar types. The proper identification of a scar, however, remains the essential first step to ensure that the appropriate laser system is chosen for treatment. The 585nm pulsed dye laser is the laser of choice for treating hypertrophic scars, keloids, erythematous scars, and striae. High-energy pulsed CO2 or erybium lasers are ideal for atrophic scars. This latter laser should not be used for proliferative lesions like hypertrophic scars or keloids because their ability to vaporize tissue may worsen or result in recurrence of the scar.
Lasers represent a major advance in scar revision despite a lack of complete understanding of their mechanism of action in collagen remodeling. Multiple studies have proven the worth of 585nm pulsed dye laser treatment in improving skin texture and pliability, as well as decreasing scar redness and associated symptoms. As laser technology continues to evolve, further improvements in managing scar tissue reactions will be made. New areas of research will likely target the remodeling phase of tissue recovery in an effort to reduce or prevent abnormal scarring before it can occur.
**Note all pictures in this article are pre and post 585nm pulsed dye laser treatment.