White lines on the outside of the thighs may be atrophy lines, or white scarring, lichen planus, florid chaffing, etc. 1. Atrophic lines: because of excessive weight, excessive obesity, resulting in excessive stretching of the thigh skin, resulting in rupture of skin elastic fibers, skin elasticity decreases, thus leading to the phenomenon of white lines on the outside of the thighs. 2. White scar: If the local skin on the outer thighs has suffered trauma, or has been operated, the white scar left after the wound healing can lead to the phenomenon of white lines on the outer thighs. 3. lichen planus: lichen planus can show the phenomenon of white lines on the outside of the thighs, mostly without conscious symptoms, occasionally accompanied by itching. 4. florid chaff rash: florid chaff rash is due to local infection of malassezia, early can show point-like white chaff rash, later can easily become a piece, into stripes, so the appearance of white lines on the outside of the thighs. There are many other reasons for the white lines on the outer thighs, and after the symptoms, it is recommended that the patient go to the hospital in time to improve the examination and take standardized treatment in accordance with the doctor’s instructions, and not to ignore the symptoms and take them lightly.