A skin papilloma 1, papillary warts: non-genuine tumors, mostly caused by viruses, manifested as surface papillae protruding outward, see a number of fine columnar protrusions, the base flat not to the epidermis extension. 2, senile pigmented warts: common in the forehead, exposed parts or trunk, can be higher than the skin, black, spot fast-like, dry surface, smooth or rough feeling. The bottom is flat and does not extend to the epidermis. If there is enlargement, bleeding and rupture, it may become cancerous and should be removed surgically. Nevus and melanoma: 1.Nevus: pigmented plaque. They are divided into (1) Intradermal nevus: rarely malignant. (2) Junctional nevus: prone to malignant transformation. (3) Mixed nevus: Intradermal nevus and junctional nevus exist at the same time. When the above nevus pigment deepens, becomes larger, itchy and painful, there is a possibility of malignant change, so it should be removed as soon as possible. 2.Melanoma: It is a highly malignant tumor with rapid development. It should be treated by wide excision. Lipoma: It is very common. It is a tumor of normal fat-like tissue, which is usually found in the extremities and trunk. It is well-defined, lobulated, hard and pseudocystic, painless. It grows slowly, but can be large in size. If it is located deep, it may become malignant and should be removed surgically in time.