Striae
Striae are very common and usually develop between the ages of 5 and 50 years.
They occur about twice as frequently in women as in men. They commonly develop during puberty, with an overall incidence of 25 percent to 35 percent, or during pregnancy, with an incidence of 77 percent.
The factors leading to the development of striae have not been fully elucidated. Striae distensae are the results of breaks in the connective tissue, resulting in dermal atrophy. Many factors, including hormones (particularly corticosteroids), mechanical stress, and genetic predisposition, appear to play a role.
During puberty, striae appear in areas where there is a rapid increase in size. In girls, the most common sites are the breasts, thighs, hips, and buttocks, whereas in boys, they are seen on the shoulders, lumbosacral region, and thighs. Other less common sites include the abdomen, upper arms, neck, and axillae.
Striae distensae are a common finding on the abdomen, and less so the breasts and thighs, of pregnant women, especially during the last trimester. They are more common in younger primigravidas than in older pregnant women. Striae gravidarum can be associated with a higher risk of lacerations during vaginal delivery.23
CLINICAL FINDINGS
Striae are usually multiple, symmetric, well-defined linear atrophic lesions that follow the lines of cleavage. Initially, striae appear as red-to-violaceous elevated lines (striae rubra) . Over time, the color gradually fades, and the lesions become atrophic, with the skin surface exhibiting a fine, white, wrinkled appearance (striae alba). The striae can measure several centimeters in length and a few millimeters to a few centimeters in width. The striae associated with systemic corticosteroid therapy and Cushing syndrome can be larger and more widely distributed.
HISTOPATHOLOGY
Histologic findings show a decrease in dermal thickness and in collagen in the upper dermis. The collagen bundles are thinned and lie parallel to the epidermis, but they are also arranged transversely to the direction of the striae. Alterations in elastic fibers are variable, but dermal elastin can be fragmented, and specific elastin staining can demonstrate a marked reduction in visible elastin content compared with adjacent normal dermis. There is absence of both hair follicles and other appendages.
DIFFERENTIAL DIAGNOSIS
The diagnosis of striae distensae is usually simple, but the differential diagnosis does include linear focal elastosis (elastotic striae) that was first described by Burket et al. in 1989. Linear focal elastosis is characterized by rows of yellow palpable striaelike bands on the lower back. Unlike striae, the lesions are raised and yellow rather than depressed and white. Elderly men are most commonly affected, although cases in teenagers have been described. Linear focal elastosis is probably not an uncommon condition. Histologically, there is a focal increase in the number of elongated or fragmented elastic fibers and a thickened dermis. It is postulated that linear focal elastosis may represent an excessive regenerative process of elastic fibers and could be thought of as a keloidal repair of striae distensae.
TREATMENT
Striae distensae have no medical consequences, but they are frequently distressing to those affected. As stretch marks tend to regress spontaneously to some degree over time, the usefulness of treatments that have been tried without case controls is difficult to assess. Topical treatments that have shown some improvement of early stage striae are: tretinoin 0.1 percent cream, a combination of 0.05 percent tretinoin/20 percent glycolic acid, or 10 percent L-ascorbic acid/20 percent glycolic acid. Several lasers have been used in treating striae: the 585-nm pulsed-dye laser has been demonstrated to be of some efficacy in improving the appearance of striae rubra but has no effect on stria alba; improvement in the leukoderma of the striae alba was noted with 308-nm excimer laser but maintenance treatment is required to sustain the cosmetic benefit.
