The current cause of brown patches on the abdomen is firstly considered as pigmented nevus on the abdomen. For the treatment of pigmented nevus on the abdomen, if the scope of the pigmented nevus does not increase significantly, the border is relatively neat, the surface is not broken and bleeding, and there are no scattered and new nodules around, it is mainly considered as benign, and this kind of pigmented nevus can be closely observed temporarily. If a pigmented nevus is found to have uneven edges, bleeding and ulceration on the surface, and scattered nodules can be found around it, it is considered malignant. For pigmented nevi with signs of malignancy, they must be removed as soon as possible and sent for pathological examination to guide the next treatment plan.