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 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 Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal bl ...

-related cysts are formed as a defense mechanism for the body following the development of

mutation In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, m ...

s that lead to an uncontrolled cellular division. Once that mutation has occurred, the affected cells divide incessantly and become cancerous, forming a

tumor A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

. 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 vessel Blood vessels are the structures of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away from ...

s, 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 Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellu ...

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 (

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, s ...

'' in the

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spin ...

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 ...

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 The urinary meatus, (, ) also known as the external urethral orifice, is the opening of the urethra. It is the point where urine exits the urethra in both sexes and where semen exits the urethra in males. The meatus has varying degrees of sensiti ...

) **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 t ...

) * Hydrocele testis (

testicle A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testostero ...

): clear fluid within the cavum vaginale * Spermatocele (

): fluid within the head of epididymis

Cutaneous and subcutaneous

Acne Acne, also known as ''acne vulgaris'', is a long-term skin condition that occurs when dead skin cells and oil from the skin clog hair follicles. Typical features of the condition include blackheads or whiteheads, pimples, oily skin, and ...

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 t ...

(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 (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 The pericardium, also called pericardial sac, is a double-walled sac containing the heart and the roots of the great vessels. It has two layers, an outer layer made of strong connective tissue (fibrous pericardium), and an inner layer made of ...

)

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 dis ...

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

* Choroid plexus cyst * Colloid cyst * Pineal gland cyst (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 patterns in both circadian and seasonal ...

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 In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bon ...

) * Subchondral cyst (cysts near the bony joints)

Seen in various locations

Dermoid cyst A dermoid cyst is a teratoma of a cystic nature that contains an array of developmentally mature, solid tissues. It frequently consists of skin, hair follicles, and sweat glands, while other commonly found components include clumps of long ...

(seen in ovaries, testes, and many other locations, from head to tailbone) * Ganglion cyst (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 Eucestoda, commonly referred to as tapeworms, is the larger of the two subclasses of flatworms in the class Cestoda (the other subclass is Cestodaria). Larvae have six posterior hooks on the scolex (head), in contrast to the ten-hooked Cestod ...

)

Neoplastic cysts

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 showi ...

atic.

Cystic fibrosis

Despite being described in 1938 as "the

microscopic The microscopic scale () is the scale of objects and events smaller than those that can easily be seen by the naked eye, requiring a lens or microscope to see them clearly. In physics, the microscopic scale is sometimes regarded as the scale be ...

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. ...

is an example of a

genetic disorder A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene (monogenic) or multiple genes (polygenic) or by a chromosomal abnormality. Although polygenic disorde ...

whose name is related to fibrosis of the cystic duct (which serves the

gallbladder In vertebrates, the gallbladder, also known as the cholecyst, is a small hollow organ where bile is stored and concentrated before it is released into the small intestine. In humans, the pear-shaped gallbladder lies beneath the liver, althoug ...

) 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 The urinary bladder, or simply bladder, is a hollow organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In humans the bladder is a distensible organ that sits on the pelvic floor. Urine enters ...

and the

, 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