Cysts, usually referred to as "epidermoid" cysts, are slow-growing, small bumps that develop beneath the skin. They are usually painless and tend to occur on the face, neck, trunk, and at times, the genital area.
Epidermoid cysts have the following characteristics:
They range in size from less than 1/4 inch to nearly 2 inches in diameter.
The cysts are round bumps that easily move under the skin when felt with the fingers.
The cysts are usually white or yellow, though people with darker skin may have pigmented cysts.
The cyst may have a central opening plugged with a blackhead. This is the remant of a hair follicle. A thick, cheese-like material can sometimes be expressed through the opening.
Epidermoid cysts, milia cysts (small, scattered cysts -- appearing like tiny, deep-seated whiteheads that never seem to come to the surface), and pilar cysts (small bump that appears on the scalp that usually has thicker walls) are not only cosmetically bothersome, they can become infected. Signs of infection include redness, swelling and pain around the cyst. Cysts can become tender and swollen, even if they're not infected and even rupture. A ruptured cyst often leads to a boil-like abscess that requires prompt treatment.