If a mole suddenly appears on the palm of the hand, it is more likely to be a pigmented mole. Pigmented nevus is a benign neoplasm composed of nevus cells, which can occur in almost everyone, from infancy to old age, and is formed by the local aggregation of melanocytes. If there is a sudden increase in color, volume, exudation, redness, swelling, ulceration, itching, pain or new lesions, it is considered that there may be malignant changes, and it is recommended to go to a regular hospital for surgical excision and dermatological examination. It is recommended to pay close attention to pigmented nevi on the palms of the hands, soles of the feet, waist and shoulders, which are stimulated by friction.