A bulge on the dorsum of the foot may be caused by trauma, tendon sheath cysts and epidermal cysts, etc. Patients are advised to take surgical treatment and medication to improve the condition. 1. Trauma: If the dorsum of the foot suffers from injuries caused by external blows, it may lead to a bulge on the dorsum of the foot. Patients need to pay attention to rest to avoid further injury to the affected area. If accompanied by infection, patients can follow the doctor’s instructions to apply antibiotic drugs, such as clindamycin, fusidic acid and so on. 2. Tendon cysts: a bulge on the back of the foot may also be caused by tendon cysts, if there is mild pain, you can follow the doctor’s instructions to take oral ibuprofen and other non-steroidal anti-inflammatory drugs, to help relieve pain. If conservative treatment fails, you can also use surgery to remove the tendon sheath tissue to reduce the recurrence rate of the disease. 3. Epidermoid cysts: Epidermoid cysts may cause a bulge on the back of the foot. Patients with epidermoid cysts can choose surgical excision to treat the disease, and after removing the cysts, the healing of the lesions can be promoted. The cause of a bulge on the dorsum of the foot is not one, it is recommended that the patient seek medical examination to clarify the cause of the disease, and cooperate with the doctor for standardized treatment.