Thighs have a white stripe may be expansion lines, florid chaff rash and other causes, according to the symptoms of specific analysis. 1. Expansion lines: when the human body is in a state of excessive obesity, short-term rapid weight gain, can lead to the skin’s elastic fiber degeneration and become more and more fragile. When it is then subjected to excessive stretching, breakage will occur, resulting in crack-like changes in the skin. Initially, the cracks may appear light red, and as time passes, the color gradually turns to white. 2. Follicular chaffing: It occurs in young adults. When the cuticle of the skin is infected with Malassezia, it can lead to the formation of florid chaff rash. At the beginning of the disease, white spots may appear, and then it can be fused into pieces or stripes. This in turn leads to white streaks on the legs. There may be other reasons for a white streak on the thigh, and you need to go to the dermatology department of the hospital in time to clarify the cause of the disease and then carry out targeted treatment.