The appearance of lumps in the arm involves many causes, and tumors are generally considered to be among the common causes, such as benign tumors, malignant tumors, soft tissue tumors, and bony tumors, which generally have local compression symptoms, and malignant tumors have more obvious symptoms and are accompanied by systemic symptoms. In addition, for example, acute injury, chronic strain injury, also due to local bleeding, hematoma compression inflammatory response resulting in local tissue adhesions, contractures, scarring, fibrosis, hyperplasia, hypertrophy and other pathological changes, in the local also feel like a lump. There are also congenital developmental malformations, due to the malformation of bone can also protrude lumps in a certain local area. There are also infections, such as localized purulent infections, which can also produce corresponding masses and produce corresponding symptoms of redness, swelling, heat, and pain. There is also heterotopic ossification, which produces bone tissue in the soft tissues after an injury, which can also lead to a lump. Therefore, there are many causes involved, and patients are advised to go to the hospital for examination.