Disorders of the Skin - Sebaceous cysts
When a sebaceous gland duct is blocked, the oil that the gland secretes cannot get to the surface of the skin. Instead, it accumulates into a hard, round, movable mass contained in a sac. This mass is known as a sebaceous cyst . Such cysts may appear on the face, back, ears, or in the genital area. A sebaceous cyst that forms on the scalp is called a wen , and may become as large as a billiard ball. The skin in this area will become bald, because the cyst interferes with the blood supply to the hair roots.
Some sebaceous cysts just disappear without treatment. However, those that do not are a likely focus for secondary infection by bacteria, and they may become abscessed and inflamed. It is therefore advisable to have cysts examined by a physician for possible removal. If such a cyst is superficial, it can be punctured and drained. One that is deeper is usually removed by simple surgical procedure in the physician's office.