A Cyst is a harmless sac-like growth in the deeper layers of the skin that contains fluid. They are typically formed from the lining of a hair follicle that gets blocked, although relatively little is known about the cause of them or why certain individuals get more than others. They are extremely common and most people will get one during their lives. The cyst sac is filled with a soft, whiting brown material that sometimes oozes out onto the skin’s surface. Occasionally they can become inflamed if the contents of the cyst rupture into the surrounding skin, causing them to be red and painful. Occasionally, bacteria can also enter the cyst and cause an infection needing to be treated with antibiotics.