A cyst is a closed sac, having a distinct envelope and division compared with the nearby tissue. Hence, it is a cluster of

cells Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery w ...

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 An abscess is a collection of pus that has built up within the tissue of the body. Signs and symptoms of abscesses include redness, pain, warmth, and swelling. The swelling may feel fluid-filled when pressed. The area of redness often extends b ...

, 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 Dysplasia is any of various types of abnormal growth or development of cells (microscopic scale) or organs (macroscopic scale), and the abnormal histology or anatomical structure(s) resulting from such growth. Dysplasias on a mainly microscopic ...

or metaplastic. ''Pseudocysts'' are similar to cysts in that they have a sac filled with fluid, but lack an epithelial lining.

Terminology

* ''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 classical Greek mythology, Syrinx (Greek Σύριγξ) was a nymph and a follower of Artemis, known for her chastity. Pursued by the amorous god Pan, she ran to a river's edge and asked for assistance from the river nymphs. In answer, sh ...

'' in the spinal cord or

brainstem The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is cont ...

is sometimes inaccurately referred to as a "cyst".

Cysts by location

Female reproductive system

Nabothian cyst A nabothian cyst (or nabothian follicle) is a mucus-filled cyst on the surface of the cervix. They are most often caused when stratified squamous epithelium of the ectocervix (portion nearest to the vagina) grows over the simple columnar epitheliu ...

(on the surface of the cervix) * Ovarian cyst (ovary) *

Paratubal cyst Paraovarian cysts or paratubal cysts are epithelium-lined fluid-filled cysts in the adnexa adjacent to the fallopian tube and ovary. The terms are used interchangeably, and depend on the location of the cyst. Topic Completed: 1 July 2013. Minor c ...

(in front of fallopian tube behind the ovary) Relative incidences of ovarian cysts

* Vaginal cysts **

Gartner's duct cyst A Gartner's duct cyst (sometimes incorrectly referred to as ''vaginal inclusion cyst'') is a benign vaginal cyst that originates from the Gartner's duct, which is a vestigial remnant of the mesonephric duct (wolffian duct) in females. They are t ...

(lateral to vaginal wall) ** Bartholin's cyst (at vaginal introitus) ** Skene's duct cyst (Beside the urinary meatus) **Ectopic ureterocoele (around the urinary meatus) **Urethral diverticulum (In front of vaginal wall)

Male reproductive system

* Rete tubular ectasia (within the rete testis) * Epididymal cyst (in the

epididymis The epididymis (; plural: epididymides or ) is a tube that connects a testicle to a vas deferens in the male reproductive system. It is a single, narrow, tightly-coiled tube in adult humans, in length. It serves as an interconnection between the ...

) * Hydrocele testis ( testicle): clear fluid within the cavum vaginale * Spermatocele ( testicle): fluid within the head of epididymis

Cutaneous and subcutaneous

* Acne cyst – Pseudocysts associated with cystic acne - an inflammatory nodule with or without an associated epidermoid inclusion cyst *

Arachnoid cyst Arachnoid cysts are cerebrospinal fluid covered by arachnoidal cells and collagen that may develop between the surface of the brain and the cranial base or on the arachnoid membrane, one of the three meningeal layers that cover the brain and the ...

(between the surface of the brain and the cranial base or on the arachnoid membrane) * Epidermoid cyst * Myxoid cyst (cutaneous condition often characterized by nail plate depression and grooves) * Pilar cyst (cyst of the scalp) * Pilonidal cyst (skin infection near tailbone) * Sebaceous cyst – sac below skin * Trichilemmal cyst – same as a pilar cyst, a familial cyst of the scalp

Head and neck

* Odontogenic cyst * Ceruminous cyst (ear) * Chalazion cyst (eyelid) * Mucous cyst of the oral mucosa * Nasolabial cyst * Thyroglossal cyst * Vocal fold cyst

Chest

* Fibrous cyst ( breast cyst) *

Pulmonary cyst A focal lung pneumatosis, is an enclosed pocket of air or gas in the lung and includes blebs, bullae, pulmonary cysts, and lung cavities. Blebs and bullae can be classified by their wall thickness. * A bleb has a wall thickness of less than 1 mm ...

(air pocket in the lung) *

Pericardial cyst A pericardial cyst is an uncommon benign dilatation of the pericardial sac surrounding the heart. It can lead to symptoms by compressing nearby structures, but is usually asymptomatic. Pericardial cysts can be congenital or acquired, and they are t ...

(abnormal dilatation of pericardium)

Abdomen

* Liver cysts ** Simple cysts ** Hydatid cysts ** Biliary cystadenoma ** Biliary cystadenocarcinoma ** Polycystic liver disease * Adrenal cyst (glands located above the kidneys) - It is a rare disease, affecting 0.06 to 0.18% of

autopsy An autopsy (post-mortem examination, obduction, necropsy, or autopsia cadaverum) is a surgical procedure that consists of a thorough examination of a corpse by dissection to determine the cause, mode, and manner of death or to evaluate any di ...

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 A pancreatic cyst is a fluid filled sac within the pancreas. Causes range from benign to malignant. Pancreatic cysts can occur in the setting of pancreatitis, though they are only reliably diagnosed 6 weeks after the episode of acute pancreati ...

* 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 Enteric duplication cysts, sometimes simply called duplication cysts, are rare congenital malformations of the gastrointestinal tract. They most frequently occur in the small intestine, particularly the ileum, but can occur anywhere along the gastro ...

Central nervous system

* Choroid plexus cyst * Colloid cyst *

Pineal gland cyst A pineal gland cyst is a usually benign (non-malignant) cyst in the pineal gland, a small endocrine gland in the brain. Historically, these fluid-filled bodies appeared on of magnetic resonance imaging (MRI) brain scans, but were more frequently d ...

(in the

pineal gland The pineal gland, conarium, or epiphysis cerebri, is a small endocrine gland in the brain of most vertebrates. The pineal gland produces melatonin, a serotonin-derived hormone which modulates sleep, sleep patterns in both circadian rhythm, circ ...

in the brain) * Glial cyst * Tarlov cyst (spinal canal)

Musculoskeletal system

* Aneurysmal bone cyst, a benign bone tumor with a radiographic cystic appearance. * Baker's cyst or popliteal cyst (behind the knee joint) * Mucoid cyst (ganglion cysts of the digits) *

Stafne static bone cyst The Stafne defect (also termed Stafne's idiopathic bone cavity, Stafne bone cavity, Stafne bone cyst (misnomer), lingual mandibular salivary gland depression, lingual mandibular cortical defect, latent bone cyst, or static bone cyst) is a depres ...

(an anatomic variant with radiographic cystic appearance in the posterior mandible) * Subchondral cyst (cysts near the bony joints)

Seen in various locations

* Dermoid cyst (seen in ovaries, testes, and many other locations, from head to tailbone) *

Ganglion cyst A ganglion cyst is a fluid-filled bump associated with a joint or tendon sheath. It most often occurs at the back of the wrist, followed by the front of the wrist. Onset is often over several months, typically with no further symptoms. Occasional ...

(hand and foot joints and tendons) * Mucoid cyst (ganglion cysts of the digits)

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

* Dermoid cyst *

Keratocystic odontogenic tumor An odontogenic keratocyst is a rare and benign but locally aggressive developmental cyst. It most often affects the posterior mandible and most commonly presents in the third decade of life. Odontogenic keratocysts make up around 19% of jaw cysts. ...

* Calcifying odontogenic cyst

Treatment

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

symptom Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormality showin ...

atic.

Cystic fibrosis

Despite being described in 1938 as "the microscopic appearance of cysts in the pancreas",

cystic fibrosis Cystic fibrosis (CF) is a rare genetic disorder that affects mostly the lungs, but also the pancreas, liver, kidneys, and intestine. Long-term issues include difficulty breathing and coughing up mucus as a result of frequent lung infections. O ...

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.

References

External links

"Cyst Symptoms and Causes"
by Melissa Conrad Stöppler, MD and William C. Shiel Jr., MD, FACP, FACR. {{Authority control Gross pathology Dermatologic terminology