What are stretch marks?
Stretch marks are fine lines on the body that occur from tissue under your skin tearing from rapid growth or over-stretching. It is a common condition that does not cause any significant medical problems but can be of cosmetic concern for some people. Other names for stretch marks are striae rubrae (which are red) and striae albae (white) striae atrophicans (thinned skin), striae gravidarum (following pregnancy), striae distensae (stretched skin), striae nigrae (black) and striae caerulea (dark blue).
Who gets stretch marks?
Stretch marks are very common, affecting 70% of adolescent girls and 40% of boys. They occur in certain areas of the body where skin is subjected to continuous and progressive stretching. These include:
- Abdomen and breast in pregnant women
- Adolescents undergoing growth spurts (thighs, buttocks, breasts)
- Shoulders in body-builders
- Obese or overweight people
Stretch marks can also occur from prolonged use of oral or topical corticosteroids and from anabolic steroids. They are also a feature of the disease Cushing syndrome, where increased adrenal cortical activity i.e. excessive circulating cortisol is implicated in their development. They are seen more often in people with Marfan syndrome.
What do stretch marks look like?
An early sign of stretch marks developing is when an area of skin becomes flattened and thin with a pink colour. This may also occasionally be itchy. Soon reddish or purplish slightly swollen lines develop perpendicular to the direction of skin tension (striae rubrae). Over time, these lighten to become whitish or flesh-coloured and much less conspicuous (striae albae). Stretch marks are usually several centimetres long and 1–10 mm wide. Those caused by corticosteroid use or Cushing syndrome are often larger and wider and may involve other regions, including the face.
The histopathological features of striae rubrae include:
- Lack of mast cells
- Structural changes in collagen bundles
- Prominent fibroblasts
- Dermal oedema
- Perivascular lymphocytes
- Reduced fibrillin microfibrils
Striae albae ressemble scar tissue:
- Epidermal atrophy
- Loss of skin appendages
- Densely packed collagen bundles parallel to the skin surface
What treatment is available?
Stretch marks usually are only a cosmetic problem, but rarely, if extensive they may ulcerate or tear easily in an accident. Stretch marks occurring in adolescents become less visible over time and generally require no treatment. In other cases, if stretch marks are a cause of concern then the following treatments, or others, may be tried, but have not been proven to be effective:
- Topical retinoid therapy
- Chemical peels
- Pulsed dye laser therapy
- Fractional thermolysis
- Skin needling