A raised pigmented nevus may be normal, but if it develops suddenly and rapidly with unclear borders, it may also be a melanoma. A pigmented nevus is narrowly defined as a benign neoplasm containing melanocytes. The cause of the nevus is not clear at this time, and it may be related to congenital heredity, developmental defects, ultraviolet radiation, trauma, and changes in hormone levels. They often appear as round or oval spots, papules or nodules, and can be either flat or slightly above the epidermis, so a raised pigmented nevus may be normal. However, if the nevus develops rapidly all of a sudden, with unclear boundaries, unsmooth edges, uneven color, and even symptoms such as itching and bleeding, the raised pigmented nevus may be abnormal, and is most commonly seen clinically as melanoma. This disease is a tumor caused by the malignant transformation of melanocytes, and the degree of malignancy is high. When you find a raised pigmented nevus, it is recommended to go to the hospital, complete a series of relevant examinations to clarify the specific cause, and if necessary, cooperate with the doctor for standardized treatment.