A cyst is a closed cavity or sac with a lining. It can be filled with fluid or semisolid material. Some of the more common cysts seen by dermatologists arise from different parts of the hair follicle.

Epidermoid or sebaceous cysts are firm, large bumps that may have a central pore or hole. Typically, they are filled with white, cheese-like material that may have an odor. Most commonly these cysts are found on the face, neck, shoulders, chest and back. They may enlarge, drain or become red or inflamed.

Pilar or trichilemmal cysts also arise from hair follicles and are typically seen as smooth, firm, rounded bumps on the scalp. Often this type of cyst does not have a central pore or hole. Occasionally this type of cyst may expel its contents or get red and inflamed.

In most cases, both types of cysts are benign and treatment can range from leaving it alone and monitoring to surgically excising or cutting out inflamed or irritated cysts.

James WD, Berger TG, Elson DM. Andrews’ diseases of the skin: clinical dermatology, 10th edition. Saunders, 2005.

Angela Leo, D.O.
Department of Dermatology
Philadelphia College of Osteopathic Medicine/Frankford Hospital
Philadelphia, Pennsylvannia.

Stephen M. Purcell, D.O., F.A.O.C.D.
Professor and Chairman of the Department of Dermatology
Philadelphia College of Osteopathic Medicine
Philadelphia, Pennsylvannia