A bulge in the back of the neck is commonly caused by the following: 1. Lipoma, the back of the neck is prone to the formation of lipoma because of the easy accumulation of fat. If the bulge is small, do not worry too much, you can reduce fat by increasing exercise appropriately. At the same time, appropriate adjustment of dietary habits can be, need to regularly go to the hospital for review. If the lipoma is larger, it needs to be surgically removed to prevent compression of nerves and other tissues; 2. Sebaceous cysts, because the area is prone to sweating, so it is easy to suffer from the disease. It can be surgically removed and sutured after going to the hospital, and then sent for pathological examination; 3, mosquito bites, you can apply local alkaline substances such as baking soda to relieve the symptoms; 4, swollen lymph nodes, there are many causes, the patient needs to go to the hospital to check the blood routine and ultrasound for clarification, if necessary, lymphatic biopsy to clarify the nature.