Most of the birthmarks will not deteriorate, only a few of them will. Birthmarks are usually divided into pigmented birthmarks and vascular birthmarks, including pigmented nevi, coffee spots, Mongolian spots, sebaceous nevi, bright red nevi, etc. 1. pigmented nevi: pigmented nevi are mostly black or brown papules with clear borders and smooth surfaces, and some of them will be elevated on the skin surface. The probability of malignant change of pigmented nevus is higher compared with other birthmarks, and the main cause is that these pigmented nevi are regularly subjected to some wear and tear and chronic stimulation; 2.Caffeinated nevus: the color is generally brown, the size varies, the boundary is clear, the surface is smooth, mostly seen in the trunk, it will not fade by itself, and generally will not deteriorate; 3.Mongolian nevus: it mostly occurs in the lumbosacral region, buttocks, back, the color is blue, generally does not need to be It will fade away in a few years, so it will not deteriorate; 4. Sebaceous nevus: it is a yellowish patch with smooth surface, and it occurs on the head, face and neck. With the development of age, it will gradually appear hyperplasia, which is mostly seen in the shape of warts. It may also deteriorate if it is subjected to friction or stimulation for a long time. 5. Erythema nodosum: It is mostly manifested as one or more red, crimson or purplish-red patches with irregular edges, not higher than the skin surface, and will fade after being pressed, mostly occurring on the head and neck. Some of the nevi may recover on their own, while the unrecovered nevi will gradually thicken, but generally will not deteriorate. When a birthmark deteriorates, it is usually accompanied by faster growth of the lesion, increased thickness, deepening of pigmentation, hair loss and crust removal, rough and broken surface, ulcers and bleeding, itching and pain, or unknown inflammation. For deteriorated birthmarks, surgical treatment, radiotherapy, systemic treatment, etc. can be taken according to the patient’s specific condition, and for some patients with more severe disease or metastasis, regional lymph node dissection is also required. Some patients may have their moles removed by doing physical, chemical, freezing, or laser treatments, but deterioration is also highly likely to occur because of incomplete treatment.