Cyst (Redirected from Cysts)

Histological micrographic image of a bronchogenic cyst of the mediastinum. Sample has been stained with hematoxylin and eosin to improve contrast.
H&E stained micrograph of a mediastinal bronchogenic cyst
SpecialtyPathology, general surgery

A cyst, also traditionally known from Old English as a wen, is a closed sac, having a distinct envelope and division compared with the nearby tissue. Hence, it is a cluster of cells that have grouped together to form a sac (like the manner in which water molecules group together to form a bubble); however, the distinguishing aspect of a cyst is that the cells forming the "shell" of such a sac are distinctly abnormal (in both appearance and behaviour) when compared with all surrounding cells for that given location. A cyst may contain air, fluids, or semi-solid material. A collection of pus is called an abscess, not a cyst. Once formed, a cyst may resolve on its own. When a cyst fails to resolve, it may need to be removed surgically, but that would depend upon its type and location.

Cancer-related cysts are formed as a defense mechanism for the body following the development of mutations that lead to an uncontrolled cellular division. Once that mutation has occurred, the affected cells divide incessantly and become cancerous, forming a tumor. The body encapsulates those cells to try to prevent them from continuing their division and contain the tumor, which becomes known as a cyst. That said, the cancerous cells still may mutate further and gain the ability to form their own blood vessels, from which they receive nourishment before being contained. Once that happens, the capsule becomes useless, and the tumor may advance from benign to cancerous.

Some cysts are neoplastic, and thus are called cystic tumors. Many types of cysts are not neoplastic, they are dysplastic or metaplastic. Pseudocysts are similar to cysts in that they have a sac filled with fluid, but lack an epithelial lining.


  • microcyst – a small cyst that requires magnification to be seen
  • macrocyst – a cyst that is larger than usual or compared to others

Related structures

A pseudocyst is very similar to a cyst, but is a collection of cells without a distinct membrane (epithelial or endothelial cells).

A syrinx in the spinal cord or brainstem is sometimes inaccurately referred to as a "cyst".

Cysts by location

Female reproductive system

Relative incidences of different types of ovarian cysts

Male reproductive system

Cutaneous and subcutaneous

Head and neck

Relative incidence of odontogenic cysts



  • Liver cysts
  • Adrenal cyst (glands located above the kidneys) - It is a rare disease, affecting 0.06 to 0.18% of autopsy studies. It constitutes 5.4 to 6.0% of adrenal gland diseases. There are five major types of adrenal cysts: simple or endothelial cysts, true or epithelial cysts, pseudocysts, parasitic cysts, and cysts not classified elsewhere. 7% of the cysts can be malignant.
  • Renal cyst (kidneys)
  • Pancreatic cyst
  • Peritoneal inclusion cyst (lining of the abdominal cavity) - It is a cluster of fluid-filled cysts lining the abdominal cavity of reproductive age women with a history of pelvic, abdominal surgeries, or abdominal inflammation. Those affected maybe presented with an abdominal, pelvic, lower back that lasted for months.
  • Enteric duplication cyst

Central nervous system

Musculoskeletal system

Seen in various locations

Infectious cysts

  • Cysticercal cyst – an infection due to the larval stage of Taenia sp. (Crain's backs)
  • Hydatid cyst – an infection in the liver or other parts of the body due to the larval stage of Echinococcus granulosus (tapeworm)

Neoplastic cysts


Treatment ranges from simple enucleation of the cyst to curettage to resection. There are cysts—e.g., buccal bifurcation cyst—that resolve on their own, in which just close observation may be employed, unless it is infected and symptomatic.

Cystic fibrosis

Despite being described in 1938 as "the microscopic appearance of cysts in the pancreas", cystic fibrosis is an example of a genetic disorder whose name is related to fibrosis of the cystic duct (which serves the gallbladder) and does not involve cysts.

This is just one example of how the Greek root cyst-, which simply means a fluid-filled sac, also is found in medical terms that relate to the urinary bladder and the gallbladder, neither of which involve cysts.

See also

This page was last updated at 2024-01-16 05:58 UTC. Update now. View original page.

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