Skin stretch marks, or striae, are skin lesions that can cause significant psychological distress to patients. Most often, pregnant women worry about their appearance, although they can also occur in adolescents, athletes, and other population groups. Among the reasons for the occurrence of stretch marks are defects in the development of the skin, as well as excessive mechanical stretching and endocrine pathologies.
Clinically and histologically, skin stretch marks (SC) are divided into 2 forms: red (CRS) (striae rubrae - initial erythematous and purple lesions) and white (BRK) (striae albae - in the form of hypopigmented, atrophic scars).
Pregnancy striae, as a rule, develop from the 24th week of pregnancy. Although the vast majority of RCs have been reported in pregnant women and adolescents, they have also been described in Cushing's syndrome and after short-term and long-term use of systemic and topical corticosteroids. In addition to this, a number of key etiological theories have been put forward. These include insufficient development of the skin (particularly elastic fibers and collagen), mechanical stretching of the skin, and endocrine imbalance.
This review of the effectiveness of DO control and method evaluation is based on a search of relevant studies in MEDLINE, Embase and Google Scholar Embase related to DO. Articles were evaluated and classified by the Oxford Center for Evidence-Based Medicine Levels of Evidence (LOE). (Table 1)
Risk factors and etiology of skin stretch marks
PK can occur during adolescence, pregnancy and obesity. The prevalence of RK among pregnant women and adolescents is varied in different authors and varies within 43%-88% and 6%-86%, respectively. Among obese individuals with a body mass index (BMI), the prevalence is reported to be 43%. Studies in other patient populations - such as non-pregnant women and adult men - also show varying prevalences (Table 2).
African-American women were more likely to have RCs than white women in the same geographic region. The prevalence and localization of RK varied depending on gender and age. Boys tend to have RCs in the lower back and knees, while women are more likely to involve the thighs and calves, and pregnant women tend to be more involved in the abdomen and chest.
Most studies of RCs have focused on pregnant women and adolescents . A positive family history is a risk factor in both of these groups. Among adolescents and children, the risk of developing RK is a high body mass index and obesity. Risk factors in women may be constitutional or pregnancy-related (Table 3).
Constitutional factors include maternal age and BMI. In young women, RCs develop more often, which is associated with the constitutional properties of the skin in young women. Pregnancy-associated factors such as birth weight, gestational age, weight gain during pregnancy, and polyhydramnios play a role in the onset of RC. (Table 4).
RCs have also been described in monozygotic twins, familial cases, and Marfan syndrome, indicating the importance of a genetic predisposition. This is supported by biopsy results showing slower rates of fibroblast migration and proliferation in RC patients.
Three main theories have been proposed related to the formation of the RC:
- mechanical stretching of the skin,
- hormonal changes,
- congenital disorder of the structure of the skin.
Mechanical stretching of the skin is disputed as despite stretching of the skin in pregnant women and on the extensor surface of the knee joints, under these conditions there is no significant increase in the incidence of RK.
RK is often found with hormonal changes. It is believed that adrenocorticotropic hormone and cortisol contribute to the activity of fibroblasts, which leads to an increase in protein catabolism and, thus, to a change in collagen and elastic fibers. In RK, an increase in skin levels of estrogen and androgen receptors in the skin, which contribute to RK, has been described compared to normal skin.
Low serum relaxin levels have been demonstrated in pregnant women with RC compared with patients without RC at 36 weeks. Skin connective tissue with less relaxin content is at greater risk of structural damage when stretched than skin with more relaxin content.
Features of skin stretch marks
Red and white RCs are different, evolutionarily related forms of RCs. Their difference in therapeutic consequences (Table 5).
Early histopathological skin changes can be detected by electron microscopy, including mast cell degranulation and macrophage activation leading to mid-dermal elastolysis. Isolation of mast cell enzymes, including elastase, is proposed as a key process initiation in the pathogenesis of RC. Changes in collagen, elastin and a low content of fibrillin are characteristic. The reorganization of fibrillin and elastin is believed to play an important role in the pathogenesis of RC. In those predisposed to the development of RK, a lack of fibrillin may be of primary importance.
Assessing the severity of skin stretch marks
There is no universal approach to assessing the severity of RC. Visual methods for its assessment have been described in the literature (Table 6).
For an objective assessment of skin relief, imaging devices, including three-dimensional (3D) cameras, confocal reflection microscopy, and epiluminescence colorimetry, may be used. They can be used as a means of assessing response to treatment at the ultrastructural level, although they have not yet been approved for specific use in RC. Epiluminescent color rendering and dermoscopy can be used to identify color in RC. Since response to treatment correlates with color, this may play a role in evaluating the therapeutic efficacy of PK treatment.
To be continued
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