A small raised lump on the arm may be dermatofibroma, sebaceous cyst, lipoma, etc. Surgical excision and other treatments can be chosen after the cause of the disease is clarified. 1. Dermatofibroma: an abnormal proliferation of fibroblasts in the dermis, a benign tumor, can be temporarily not dealt with, such as rapid growth, can choose surgical excision. 2. Sebaceous cysts: commonly known as “powder tumor”, due to poor sebaceous gland discharge, the contents of the capsule gradually increased, preferably in young adults, it is recommended that surgical excision, such as left untreated, there is the possibility of infection and ulceration. 3. Lipoma: it is a kind of benign soft tissue tumor caused by gathering of local adipose tissue, if there is no special discomfort, it can be left unattended, if it grows gradually or causes local discomfort, it can be chosen to be surgically removed. If there is a raised lump on the arm, it is recommended to go to the hospital for consultation, and after clear diagnosis, choose targeted treatment.