Outpatient clinics often encounter a swelling on the skin, and patients often ask: Is something wrong? Will it become malignant? If any of the following conditions should be dealt with: 1, asymmetry (Asymmetry, A), asymmetry of the skin swelling; 2, Border (Border, B), border is not clear; 3, Color (Color, C), color refractory, bright; 4, Diameter (Diameter, D), greater than 6mm, larger than a pencil eraser; 5, elevation (Elevation, E), progress (Evolving, E), the swelling has changed. Elevation,E), Evolving,E), the swelling has changed. If the skin swelling has existed in the past, there have been recent changes, such as enlargement, elevation, ulceration and bleeding need to be dealt with, such as no change can be observed. If it is a new swelling, the growth is faster (more than 6mm in 3 months) when timely hospital consultation.