Blood nevus is what people usually call vascular nevus, also called capillary nevus. Usually, when a person is about 30 years old or older, he or she will start to develop more or less capillary nevi in various parts of the body. This kind of capillary nevus actually appears as a red, pinpoint-like papule, similar to a mole, and may fade when pressed slightly with a toothpick or a cotton swab. This kind of blood nevus is actually harmless to human body, and its formation is mainly due to the superficial layer of capillaries, the local formation of hyperplasia or capillary expansion, and the formation of capillary hemangioma. However, the extent of this kind of capillary hemangioma is very small, only the size of a grain of rice at most, so it does not have any substantial harm to human body.