A nevus is also known as a pigmented mole. A purple nevus on the foot that gradually gets bigger is usually caused by irritation, localized trauma, and malignant cancer. 1. Repeated irritation, repeated rubbing of the nevus area, or scratching by the patient’s own hands will lead to localized and obvious enlargement of the nevus. 2. Gradual enlargement of nevus may also be due to external damage, such as traumatic stimulation leading to nevus site rupture and bleeding, or accidentally scratched, etc., which will appear to be enlarged after healing. 3. nevus gradually become bigger, should be alert to whether due to the occurrence of malignant changes, because in the pigmented nevus malignant changes, will occur obvious enlargement, and usually manifested in an irregular shape. It is recommended to go to the hospital for examination and treatment in time. Patients should avoid the nevus area from external stimulation and injury to ensure its cleanliness and safety. Usually, attention should be paid to observation, if the nevus is found to grow too fast, break or bleed, surgical excision treatment should be carried out under the guidance of doctors to prevent the nevus cells from remaining and leading to recurrence.