Strias are scars located in the deepest layer of the skin - the dermis. The basis for the formation of stretch marks is the formation of small tears in stretch locations. Gradual healing causes connective tissue to form in stretch locations. Visually it looks like a scar – it is a stretch mark.
Typically, stretch marks are flat or lower from the surface of the skin. Strias are the scars located on the deeper layer of the skin - the dermis - resulting from excessive stretching of the collagen fibers and their tearing. The most commonly stretch marks occur in the teenage body, when the the body develops rapidly. During pregnancy this process also occurs.

For example, in the United States, strias occur ~ 90% in pregnant women, 70% in puberty girls and 40% in teenage boys (many of them doing sports). Strias appear on women 6 times more than men.
Strias are rather a cosmetic problem, but depending on their depth and extent, they can affect the patient's quality of life.
In recent years, stretch marks have also been seen developing in adult women, especially on the outer surfaces of the buttocks, and even those who are not overweight and who lack familial predisposition to stretch marks.


The most common source that strias occur is:

Pregnancy, familial predisposition, connective tissue weakness, obesity, hormonal therapy, oral therapy with glucocorticosteroid hormones and local treatment with steroid-containing creams for long periods of time on large surfaces. An important part in the development of strias may also be: environmental factors, lifestyle, sport (for example, athletes who have rapid changes in the body), nutrition, increased hormone intake (including hormonal contraceptives).


Strias occur in places where the skin resistance to stretching has fallen and where more fat is deposited. For women, these places include hips, thighs, buttocks, belly and breasts. Men develop stretch marks on the back, back of the lumbar, and the outer sides of the thighs.


At the initial stage, the stretch marks are reddish or purple stripes, which may be slightly dense, wrinkled or having different texture from surrounding skin. Luckily, in time the strias turn into the skin color or will be brighter, but sometimes they will also turn darker.
Strias can be both vertical and horizontal. Men are more likely to have horizontal strias, which are related to increased growth.
Strias can be:
atrophic - below the whole surface of the skin. Most strias are atrophic.
normotrophic – same level as the skin.
hypertrophic - higher from the skin surface.