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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 is a closed sac, having a distinct envelope and division compared with the nearby tissue. Hence, it is a cluster of cells that has 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 tumour. The body encapsulates those cells to try to prevent them from continuing their division and contain the tumour, 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 tumour 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[1]

Male reproductive system

Cutaneous and subcutaneous

Head and neck

Relative incidence of odontogenic cysts[2]



Liver cysts


  • Adrenal cyst: Types of adrenal cysts include parasitic cysts, epithelial cysts, endothelial cysts, and pseudocysts. 56% of all adrenal cyst-like changes are pseudocysts, and only 7% of those pseudocysts are malignant or potentially malignant.[4]
  • Renal cyst (kidneys)
  • Pancreatic cyst[5]
  • Peritoneal cyst (lining of the abdominal cavity)

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.[8]

Cystic fibrosis

Despite being described in 1938 as "the microscopic appearance of cysts in the pancreas",[9] 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.[10]

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


  1. ^ Abduljabbar HS, Bukhari YA, Al Hachim EG, Alshour GS, Amer AA, Shaikhoon MM, Khojah MI (July 2015). "Review of 244 cases of ovarian cysts". Saudi Medical Journal. 36 (7): 834–8. doi:10.15537/smj.2015.7.11690. PMC 4503903. PMID 26108588.
  2. ^ Borges LB, Fechine FV, Mota MR, Sousa FB, Alves AP (2012). "Odontogenic lesions of the jaw: a clinical-pathological study of 461 cases". Revista Gaúcha de Odontologia. 60 (1).
  3. ^ a b c d e Rawla P, Sunkara T, Muralidharan P, Raj JP (March 2019). "An updated review of cystic hepatic lesions". Clinical and Experimental Hepatology. 5 (1): 22–29. doi:10.5114/ceh.2019.83153. PMC 6431089. PMID 30915403.
  4. ^ Kar M, Pucci E, Brody F (October 2006). "Laparoscopic resection of an adrenal pseudocyst". Journal of Laparoendoscopic & Advanced Surgical Techniques. Part A. 16 (5): 478–81. doi:10.1089/lap.2006.16.478. PMID 17004872.
  5. ^ Stark, Alexander; Donahue, Timothy R.; Reber, Howard A.; Hines, O. Joe (2016-05-03). "Pancreatic Cyst Disease: A Review". JAMA. 315 (17): 1882. doi:10.1001/jama.2016.4690. ISSN 0098-7484.
  6. ^ Zadik Y, Aktaş A, Drucker S, Nitzan DW (December 2012). "Aneurysmal bone cyst of mandibular condyle: a case report and review of the literature". Journal of Cranio-Maxillo-Facial Surgery. 40 (8): e243-8. doi:10.1016/j.jcms.2011.10.026. PMID 22118925.
  7. ^ Bancroft, Laura W; Peterson, Jeffrey J; Kransdorf, Mark J (January 2004). "Cysts, geodes, and erosions". Radiologic Clinics of North America. 42 (1): 73–87. doi:10.1016/S0033-8389(03)00165-9.
  8. ^ Zadik Y, Yitschaky O, Neuman T, Nitzan DW (July 2011). "On the self-resolution nature of the buccal bifurcation cyst". Journal of Oral and Maxillofacial Surgery. 69 (7): e282-4. doi:10.1016/j.joms.2011.02.124. PMID 21571416.
  9. ^ Andersen DH (1938). "Cystic fibrosis of the pancreas and its relation to celiac disease". American Journal of Diseases of Children. 56 (2): 344–399. doi:10.1001/archpedi.1938.01980140114013.
  10. ^ Greenholz SK, Krishnadasan B, Marr C, Cannon R (February 1997). "Biliary obstruction in infants with cystic fibrosis requiring Kasai portoenterostomy". Journal of Pediatric Surgery. 32 (2): 175–9, discussion 179–80. doi:10.1016/S0022-3468(97)90174-3. PMID 9044117.

External links

External resources