Lymphadenitis is the medical term for enlargement in one or more lymph nodes, usually due to infection. Lymph nodes are filled with white blood cells that help your body fight infections. When lymph nodes become infected, it's usually because an infection started somewhere else in your body. Rarely, lymph nodes can enlarge due to cancer.
You have about 600 lymph nodes in your body, but normal lymph nodes may only be felt below your jaw, under your arms, and in your groin area.
A normal lymph node is small and firm. When lymph nodes become infected, they usually increase in size, become tender, and may be felt in other areas of your body during a physical exam.