Medically reviewed by Susan Bard, MD Boils are painful, pus-filled, and are caused by infections like Staphylococcus ...

A cyst is a sac of tissue containing fluid or air that can form in many areas of the body. Cysts often do not need to be removed unless they are causing pain or other problems. There are several ...

What Is a Dermoid Cyst? A dermoid cyst is an abnormal growth of non-cancerous tissue under the skin. These cysts may contain hair follicles, skin tissue, sweat, and oil. Sometimes cysts also contain ...

An epidermoid cyst is a lump under the skin. Epidermoid cysts usually do not require treatment, unless a person wants to have them removed due to cosmetic reasons, or if the cyst becomes infected.