Common pigmented nevus and melanoma can usually be distinguished by symptoms and pathological examination. 1. Symptoms: common nevus has different types, so it develops in different locations, some of them occur in the head and face, some of them occur in the limbs and trunk, and the color of lesions varies, and the forms are spots, papules, patches or plaques, etc. On the other hand, patients with melanoma will have the original nevus increase rapidly and have signs such as itching and bleeding. Melanoma patients will have the original nevus rapidly enlarged and bulging, and will have signs such as itching and bleeding, which will gradually develop into ulcers, and will not be healed again and again. When it develops to the late stage, bone metastasis, lung metastasis, craniocerebral metastasis and so on will also occur. 2. Pathology: most of the common nevi are benign lesions, doctors need to take a small part of tissue from the lesion, make a slice and put it under the microscope for observation. Pathological examination is a necessary step to confirm the diagnosis of melanoma, which can directly confirm the diagnosis of melanoma and its grading and staging. Patients who are suspected of having melanoma are recommended to go to the hospital in time and make a clear diagnosis through standardized examination under the guidance of doctors, and it is not recommended to judge on their own.