Moles here refer to pigmented nevi, which grow suddenly within a few days and may be related to infection or malignant changes. 1. Infection: a mole is a benign tumor on the surface of the skin, which normally grows slowly and does not cause serious effects on the body except affecting the aesthetic appearance. When suppurative infection occurs due to some external stimuli, the volume of nevus will grow rapidly because of the increase of purulent secretion. Symptoms can be improved after targeted anti-infection treatment. 2. Malignant transformation: pigmented nevus has a certain chance of malignant transformation, when pigmented nevus has rapid growth or abnormal changes in shape, it is necessary to be alert to the possibility of malignant transformation. In this case, it is necessary to go to the regular hospital for consultation and pathological section examination in time, and perform surgical excision treatment in time if necessary. Due to the rapid change of the disease, the specific situation must be timely to ask the doctor for a face-to-face consultation.