A lump behind the ear can have many possible causes. The most common include swollen lymph nodes caused by an uncomplicated infection. These lumps are typically harmless and relatively easy to treat.

Riding in jeeps, touring in tanks and taking the bumps of basic training have caused such an increase in pilonidal-cyst disorders that some doctors call them jeep disease. Cause: an infection of a ...

Pilonidal sinus—also called a pilonidal cyst—is a skin infection that occurs in or around the crease of your buttocks. This condition happens when hair, skin cells, and dirt clog a hair ...