A one-year-old baby with lumps on the left side of the neck may be related to enlarged lymph nodes, mosquito bites, benign tumors and other causes. 1. swollen lymph nodes: due to viral, bacterial and other invasions, can cause reactive hyperplasia of the neck lymph nodes, manifested as swollen lymph nodes to form lumps. 2. Mosquito bites: If the left side of the neck of a one-year-old baby is bitten by mosquitoes, it will cause the body to have a metamorphic reaction and form a lump in the local area, which can be swollen, itchy, painful and other manifestations. 3. Lipoma: Lipoma is a kind of soft tissue benign tumor, which will be manifested as a small lump when it appears in the neck. Lipoma generally does not need special treatment, if its volume is large or affects the aesthetic appearance, lipoma excision can be carried out. One year old baby with lumps on the left side of the neck suggests that parents take their children to the hospital in a timely manner to clarify the cause of the disease and standardize the treatment under the guidance of the doctor.