The bulge behind the neck is commonly due to the following reasons: 1. Lipoma, the back of the neck is prone to the formation of lipoma because it is prone to the accumulation of fat. If the bulge is small, don’t worry too much, you can reduce fat by increasing exercise properly. At the same time, you can adjust your diet appropriately, and you need to go to the hospital regularly for rechecking. If the lipoma is large, it needs to be surgically removed to prevent compression of nerves and other tissues; 2. Sebaceous cysts are easy to suffer from the disease because the area is prone to sweating. You can go to the hospital to clarify the surgical resection and suture, and then sent to the pathology examination; 3, mosquito bites, you can locally apply alkaline substances, such as baking soda to relieve the symptoms; 4, lymph node enlargement, which has a lot of causative factors, the patient needs to go to the hospital to check the blood routine and ultrasound for clarification, and if necessary, the nature of the lymph biopsy to clarify.