A cyst is a collection of material (usually white, cheesy, or firm) contained in a cyst wall that grows in the upper layer of the skin. There are several different kinds of cysts. They can occur on any skin surface but are most common on the face, neck, scalp, chest and back. A cyst may be totally asymptomatic, or it may hurt when touched. It can also release pus.
Cysts do not have to be removed unless they are cosmetically unacceptable or they get irritated, inflamed or infected. An infected cyst is typically red, swollen, painful, and sometimes extrudes pus. It can be treated with antibiotics and then removed once inflammation subsides.