Postpartum striae rubra is common, and in Asian skin, these lesions can progress to become hyperpigmented striae distensae. Results from a consecutive case series show the utility of nonablative fractional photothermolysis for treating this problem.
In late 2009, Dr. Belo presented her experience using this laser-based approach in six patients with postpartum striae rubra of one to two months duration at the Joint Meeting of the American Society for Dermatologic Surgery (ASDS) and American Society of Cosmetic Dermatology and Aesthetic Surgery (ASCDAS).
The protocol consisted of a series of six treatments at four-week intervals and included a topical treatment regimen applied for one week after each session to mitigate the development of postinflammatory hyperpigmentation, which is a particular risk in Asian skin.
Clinical and photographic evaluation showed all women benefited, with progressive improvement in the appearance of the striae rubra and overall skin texture without significant adverse effects. The assessments showed decreases in lesion color, length, width and depth, as well as increased elasticity of the treated skin.
"In Asian women, postpartum striae rubra can progress to become permanent hyperpigmented lesions. We have tried multiple interventions to improve the appearance of striae rubra and prevent their worsening, but the various modalities have had limitations in terms of efficacy, side effects and/or tolerability," Dr. Belo says.
"We have had good success using fractional photothermolysis with the 1,550 nm erbium:glass laser for various off-face indications and are excited to see it is a valuable tool for treating postpartum striae rubra, considering it is a very common cosmetic concern," she says.
The women enrolled in the study had Fitzpatrick skin type III-V. Standard laser parameters were used, consisting of an energy level of 30-40 mJ/cm2, depth of 900 to 1,120 microns, treatment level 4 (200 MTZ/cm2) and eight passes (25 MTZ/cm2).
Post-treatment, women applied two topical creams twice daily for five days: an anti-inflammatory cream combining hydrocortisone with erythromycin cream and a tyrosinase inhibitor cream containing arbutin, kojic acid and vitamin C.
Changes in striae rubra appearance were rated using a well-established, five-point quartile grading system, where 0 = no improvement or worsening, and 4 = greater than 75 percent improvement.
In addition, biopsies were obtained at baseline and at one, three and six months for histological analysis.
Improved clinical appearance was first noted at the second treatment session, and at each successive visit there were further positive changes.
At the final assessment, all women achieved the maximum score of 4 in the quartile grading; the minimum rating of improvement was 80 percent; and three women were judged to achieve 90 percent improvement.
"All women developed erythema and bronzing after each session, but these sequelae were transient," Dr. Belo says. "We saw no problems with postinflammatory hyperpigmentation nor any progression of the striae rubra to hyperpigmented striae.
"In fact, hyperpigmented striae distensae present in two women improved in appearance, as did linea nigra, which was present in all women," she says.
The findings in histological assessment paralleled the clinical changes, showing a decrease in inflammatory infiltrate, decreased fragmentation of elastic fibers and a significant increase in the number of normal fibers by one month.
The serial histological evaluations demonstrated resolution of inflammation and continued connective tissue remodeling.
Mechanism of action
The rationale for using fractional photothermolysis to improve the appearance of striae rubra is based on the concept that striae rubra are an early manifestation of a wound-healing process that progresses to permanent atrophic scarring.
Timely intervention with the laser treatment during the inflammatory and early proliferative phases favorably alters the remodeling process by accelerating the early wound-healing stages and promoting earlier and normal maturation.
"Visible redness resolves initially as a consequence of shortening of the inflammatory and proliferative stages and … also as new blood vessels, which develop during those phases, undergo apoptosis.
"Textural changes are a result of treatment-induced deposition of organized bundles of new collagen and elastic fibers," Dr. Belo says.
She suggests that the laser treatment first induces collagen degradation and upregulates the release of inflammatory mediators that regulate production of new collagen and elastin.
When the rates of collagen degradation and synthesis match, the maturation phase of wound healing begins.
"In normal wound healing, the latter phase usually occurs between six and 12 months, but it was already evident by histology at three months in these patients," Dr. Belo says.
The improvement in hyperpigmented striae and linea nigra may be explained by treatment-induced formation of microscopic epidermal necrotic debris that acts to transport melanin from the basal cell layer to the skin surface, where it is expelled. DT
Disclosure: Dr. Belo reports no relevant financial interests.