It is called spider nevus because it has a central point nevus body that is flat on the skin and then surrounded by small blood vessels branching in a radial shape as spider feet, which are located under the skin, flat, and shaped like a spider and so named. When the mole body is pressed with an object, the spider nevus will disappear, and when the pressure is lifted, the blood will fill from the center outward from the mole body, which is its great characteristic. The size of spider nevus is different, small ones are in the shape of dots and large ones can reach 1.5 cm in diameter, often occurring on the face, neck, and hands, etc., and can be single or multiple. The cause of spider nevus is due to elevated estrogen levels, which are often seen in acute and chronic hepatitis, cirrhosis and other diseases, resulting in increased estradiol and estrone in the blood due to impaired liver function and abnormal expansion of small arterial capillaries.