A bacterial or viral infection can cause preauricular lymph node enlargement. These lymph nodes are located directly in front of the ears.
Enlarged lymph nodes can also be a sign of cancer or immune system disorders, according to WebMD. Enlarged lymph nodes that are tender to the touch and feel warm often indicate an infection, while lymph nodes that are firm and painless are more indicative of malignant diseases. On occasion, lymph nodes can stay permanently enlarged following an infection. When this occurs, they are referred to as "shotty" lymph nodes. Lymph nodes smaller than 1 cm are usually considered to be normal in size.