A swelling in front of an ear is most likely caused by an enlarged parotid gland, which is the largest salivary gland. Parotid gland swelling may have several causes, including parotid gland stones (which block the tube leading saliva from the gland to the mouth), infection, diabetes, and tumors. Swelling behind the ear is typically a result of an enlarged lymph node. People also refer to this condition as having swollen glands or swollen lymph nodes. Lymph nodes can be found in many places in the body, including the groin, armpits, neck, and behind the ears.