A cyst is an abnormal, sac-like structure that can be found anywhere in the body. Cysts usually contain a gaseous, liquid, or semisolid substance and have an outer wall, known as the capsule. Cysts may be small and visible only under a microscope, or they may grow to a very large size and displace normal body structures.
Cysts occur commonly in numerous tissues and organs and are often named according to their particular anatomic location (for example ovarian cysts, bladder cysts, breast cysts, liver cysts, kidney cysts, pancreatic cysts, vaginal cysts, skin cysts, thyroid cysts).
The majority of small cysts have no symptoms or signs. However, sometimes the cysts can be felt as a lump or bump in the skin or even in the tissues beneath the skin. Sometimes these cysts are painful. Cysts not associated with the skin but with internal organs may not produce any symptoms if they are small. If the cysts become large and displace or compress other organs or block normal fluid flows in tissues like the liver, pancreas, or other organs, then symptoms related to those organs may develop.