If there are lines on the buttocks, they are usually considered to be swelling lines, also called atrophy lines, which are usually associated with rapid weight gain in a short period of time and the breakage of subcutaneous fibers, which will appear on the skin. Initially, the lines may be purplish red and will gradually turn white, but there is no discomfort and again, no special treatment is needed. These lines may also appear on the stomach and thighs, which are the same as stretch marks. Children in adolescence may also have horizontal lines on the waist and knees because they are growing too fast, which are all part of the same problem. These skin lines usually do not require special treatment, and this phenomenon does not cause other lesions or various discomforts, and will slowly fade with time. If there are lines on the buttocks, they are usually considered to be expansion lines, also called atrophy lines, and if you want to avoid them, you should try to control your weight and not show rapid weight gain in a short period of time.