Cyst has the following definitions in the field of medicine.

1. A bladder. A bladder is a type of organ that can widen in order to hold fluid. An example is the urinary bladder, which is a hollow, muscular organ in the body that collects and temporarily holds urine (pee) until it is ready to leave the body.

2. An abnormal lump, swelling, or sac that contains fluid, a part solid material, or a gas, and is covered with a membrane. A membrane is a thin layer of flexible tissue that covers something. Cysts are present in and under the skin. They can be present in any organ, tissue, or body opening and are usually harmless. However, some cysts interfere with the proper functioning of organs or tissues that they grow in or on. In addition, cysts can look bad. Cysts can also be cancerous. In many cases, cysts can be removed with surgery.

There are many different types of cysts and the causes of cysts are also numerous. Some cysts can be formed by a buildup of material that is caused by blockage of a duct (a narrow tube) that comes from a fluid-forming gland. A gland is an organ in the body made of special cells that form and release materials such as fluid. A cell is the smallest, most basic unit of life, that is capable of existing by itself.
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