The scalp, ears, back, face, and upper arm, are common sites for sebaceous cysts, though they may occur anywhere on the body except the palms of the hands and soles of the feet. In males a common place for them to develop is the scrotum and chest.
In most cases, lumps or nodules behind the ears are harmless. They may signal a need for medication, as in the case of an infection, but they rarely are a sign of a dangerous or life-threatening problem.
Many bacterial and viral infections can cause swelling in and around your neck and face. Two such infections are strep throat and infectious mononucleosis (Epstein-Barr virus). Other conditions can also cause swelling in and around the neck and face.