Stretch marks may appear on a woman's stomach when she becomes pregnant, because of the rapid stretching of skin from the baby growing and developing -- but stretch marks can occur on almost any part of your body. You can develop stretch marks on your thighs, the backs of your knees, near your underarms and even on your sides.
Rapid weight gain can cause stretch marks on your hips, thighs and the backs of your knees. Even if you lose the weight you've put on, the stretch marks will still be there. Over time, they may fade and become less noticeable. If you're lifting weights, you may also notice new stretch marks appearing on your arms and legs as your muscle mass grows and stretches the skin rapidly.
Rapid Growth Spurts
If you grew very rapidly during puberty, your skin may have stretched too far and fast, resulting in stretch marks on your legs or even your sides, according to MedlinePlus. Rapid growth during puberty can result in stretch marks for both men and women. Unfortunately, there's no way to slow puberty or growth, and the stretch marks are permanent. Certain creams can help fade stretch marks and scars.
Certain medical conditions such as Cushing's syndrome, Marfan syndrome, Ehlers-Danlos syndrome and other genetic disorders can produce stretch marks. When your adrenal glands become affected by these medical conditions, stretch marks can be widespread all over your body, including your legs. Certain creams such as corticosteroids and lotions can also cause stretch marks to appear if you're applying them on your legs. Oral steroids can also cause stretch marks to appear on your legs.