A lump inside the child’s chin may be caused by sebaceous cysts, lipomas, lymph nodes and other reasons. 1. Sebaceous cysts: this is due to the sebaceous gland ducts are blocked, sebum stagnation to form cysts, facial skin sebaceous glands are rich, there are lumps in the chin may be sebaceous cysts. 2. Lipoma: the cause is unknown, but it is considered that under the stimulation of various factors, normal fat cells proliferate abnormally to form lipoma, which is a benign tumor without symptoms and most of them do not need treatment. 3. Lymph nodes: submandibular lymph nodes are widely distributed, and may be infected by pathogenic microorganisms, causing lymph node hyperplasia and enlargement, and the nodes with good mobility can be touched under the skin. A child with a lump on the chin may also be related to other causes, you can go to the hospital to do the relevant examination, a clear diagnosis before treatment.