Submental ln swelling in 6 years old child?

The size is importan: A 6 y/o may have a submental node or two normally, but they are usually small, smaller than 1/2 inch. When it is infected, it may be red and/or tender. It is extremely rare for a small child to have a cancer in the submental node only. A viral infection as the cause is a possibility. It may be a lymph node, but maybe a thyroglossal cyst if it is in the midline. I would have a doctor take a look.