White spots on the skin of the limbs are mostly considered to be caused by idiopathic pitting white spots, lichen planus and vitiligo. 1. Idiopathic pitting white spots: also known as senile white spots, caused by localized melanocyte reduction. With increasing age, melanocyte apoptosis or melanocyte loss. Patients will show round or oval white spots, the color gradually turns from white to porcelain white, the border is clear, with the increasing age, the number of white spots will continue to increase. 2. lichen planus: a superficial infection caused by Malassezia violating the cuticle of the skin. The skin lesions at the beginning of the pores for the center, the border is clear point-like rash, can be brown, light brown, light red, yellowish or white, neighboring lesions can be fused with each other into an irregular large piece, the surface is covered with chaffy scales. 3. Vitiligo: Vitiligo is a common pigment loss skin disease, if the melanocyte synthesis of melanin or melanin transporter link obstacle, will induce melanin deficiency, can not maintain normal skin color, ultimately lead to vitiligo. Vitiligo can occur in all parts of the body, and when it involves the limbs, there will be white spots on the skin. The patient limbs skin white spots, should go to the local hospital, identify the cause of the disease, follow the doctor’s instructions for treatment.