A cyst is a closed sac, having a distinct envelope and

division Division or divider may refer to: Mathematics *Division (mathematics), the inverse of multiplication *Division algorithm, a method for computing the result of mathematical division Military *Division (military), a formation typically consisting ...

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 Pus is an exudate, typically white-yellow, yellow, or yellow-brown, formed at the site of inflammation during bacterial or fungal infection. An accumulation of pus in an enclosed tissue space is known as an abscess, whereas a visible collection ...

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 Surgery ''cheirourgikē'' (composed of χείρ, "hand", and ἔργον, "work"), via la, chirurgiae, meaning "hand work". is a medical specialty that uses operative manual and instrumental techniques on a person to investigate or treat a pa ...

, 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 b ...

-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 replication, DNA or viral repl ...

s that lead to an uncontrolled

cellular division Cell division is the process by which a parent cell divides into two daughter cells. Cell division usually occurs as part of a larger cell cycle in which the cell grows and replicates its chromosome(s) before dividing. In eukaryotes, there are ...

. 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 The blood vessels are the components 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 ...

s, from which they receive nourishment before being contained. Once that happens, the capsule becomes useless, and the tumor may advance from

benign Malignancy () is the tendency of a medical condition to become progressively worse. Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not s ...

to cancerous. Some cysts are

neoplastic 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 ...

, and thus are called cystic tumors. Many types of cysts are not neoplastic, they are dysplastic or

metaplastic Metaplasticity is a term originally coined by W.C. Abraham and M.F. Bear to refer to the plasticity of synaptic plasticity. Until that time synaptic plasticity had referred to the plastic nature of ''individual'' synapses. However this new form re ...

. ''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 intercell ...

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 Pseudocysts are like cysts, but lack epithelial or endothelial cells. Initial management consists of general supportive care. Symptoms and complications caused by pseudocysts require surgery. Computed tomography (CT) scans are used for initial ima ...

'' is very similar to a cyst, but is a collection of cells without a distinct membrane (

endothelial The endothelium is a single layer of squamous endothelial cells that line the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the rest of the vessel ...

cells). A '' syrinx'' 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 sp ...

or brainstem is sometimes inaccurately referred to as a "cyst".

Cysts by location

Female reproductive system

* Nabothian cyst (on the surface of the cervix) *

Ovarian cyst An ovarian cyst is a fluid-filled sac within the ovary. Often they cause no symptoms. Occasionally they may produce bloating, lower abdominal pain, or lower back pain. The majority of cysts are harmless. If the cyst either breaks open or causes ...

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

Vaginal cysts Vaginal cysts are uncommon benign cysts that develop in the vaginal wall. The type of epithelial tissue lining a cyst is used to classify these growths. They can be congenital. They can present in childhood and adulthood. The most common type is ...

** Gartner's duct cyst (lateral to vaginal wall) **

Bartholin's cyst A Bartholin's cyst occurs when a Bartholin's gland within the labia becomes blocked. Small cysts may result in minimal or no symptoms. Larger cysts may result in swelling on one side of the vagina, as well as pain during sex or walking. If the cys ...

(at vaginal introitus) **

Skene's duct cyst In female human anatomy, Skene's glands or the Skene glands ( , also known as the lesser vestibular glands, paraurethral glands) are glands located around the lower end of the urethra. The glands are surrounded by tissue that swells with blood d ...

(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 sensit ...

) **Ectopic ureterocoele (around the urinary meatus) **Urethral diverticulum (In front of vaginal wall)

Male reproductive system

* Rete tubular ectasia (within the

rete testis The rete testis ( ) is an anastomosing network of delicate tubules located in the hilum of the testicle (mediastinum testis) that carries sperm from the seminiferous tubules to the efferent ducts. It is the counterpart of the rete ovarii in fe ...

) * Epididymal cyst (in the epididymis) *

Hydrocele testis A hydrocele testis is an accumulation of clear fluid within the cavum vaginale, the potential space between the layers of the tunica vaginalis of the testicle. It is the most common form of hydrocele and is often referred to simply as a "hydrocele ...

(

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 testoste ...

): clear fluid within the

cavum vaginale The tunica vaginalis is the pouch of serous membrane that covers the testes. It is derived from the vaginal process of the peritoneum, which in the fetus precedes the descent of the testes from the abdomen into the scrotum. After its descent, ...

Spermatocele Spermatocele is a fluid-filled cyst that develops at the top of the testicle of the epididymis. The fluid is usually a clear or milky white color and may contain sperm. Spermatoceles are typically filled with spermatozoa and they can vary in size ...

(

): 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 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 po ...

- an inflammatory nodule with or without an associated epidermoid inclusion cyst * Arachnoid cyst (between the surface of the brain and the cranial base or on the arachnoid membrane) *

Epidermoid cyst An epidermoid cyst or epidermal inclusion cyst is a benign cyst usually found on the skin. The cyst develops out of ectodermal tissue. Histologically, it is made of a thin layer of squamous epithelium. Signs and symptoms The epidermoid cyst may ...

Myxoid cyst A myxoid cyst is a cutaneous condition often characterized by nail plate depression and grooves. See also * Scleroderma * List of cutaneous conditions * List of radiographic findings associated with cutaneous conditions Many conditions of ...

(cutaneous condition often characterized by nail plate depression and grooves) * Pilar cyst (cyst of the scalp) *

Pilonidal cyst Pilonidal disease is a type of skin infection which typically occurs as a cyst Intergluteal cleft, between the cheeks of the buttocks and often at the upper end. Symptoms may include pain, swelling, and redness. There may also be drainage of flui ...

(skin infection near tailbone) *

Sebaceous cyst A sebaceous cyst is a term commonly used to refer to either: * Epidermoid cysts (also termed epidermal cysts, infundibular cyst) * Pilar cysts (also termed trichelemmal cysts, isthmus-catagen cysts) Both of the above types of cysts contain ker ...

– sac below skin * Trichilemmal cyst – same as a pilar cyst, a familial cyst of the scalp

Head and neck

Odontogenic cyst Odontogenic cyst are a group of jaw cysts that are formed from tissues involved in odontogenesis (tooth development). Odontogenic cysts are closed sacs, and have a distinct membrane derived from rests of odontogenic epithelium. It may contain air ...

* Ceruminous cyst (ear) * Chalazion cyst (eyelid) * Mucous cyst of the oral mucosa * Nasolabial cyst *

Thyroglossal cyst A thyroglossal cyst is a fibrous cyst that forms from a persistent thyroglossal duct. Thyroglossal cysts can be defined as an irregular neck mass or a lump which develops from cells and tissues left over after the formation of the thyroid gland dur ...

Vocal fold cyst Vocal fold cysts (also known as ''vocal cord cysts'') are benign masses of the membranous vocal folds. These cysts are enclosed, sac-like structures that are typically of a yellow or white colour. They occur unilaterally on the midpoint of the med ...

Chest

* Fibrous cyst (

breast cyst A breast cyst is a cyst, a fluid-filled sac, within the breast. One breast can have one or more cysts. They are often described as round or oval lumps with distinct edges. In texture, a breast cyst usually feels like a soft grape or a water-filled ...

) * Pulmonary cyst (air pocket in the lung) * Pericardial cyst (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 o ...

)

Abdomen

* Liver cysts ** Simple cysts **

Hydatid cyst Echinococcosis is a parasitic disease of tapeworms of the ''Echinococcus'' type. The two main types of the disease are ''cystic echinococcosis'' and ''alveolar echinococcosis''. Less common forms include ''polycystic echinococcosis'' and ''unic ...

s ** Biliary cystadenoma ** Biliary cystadenocarcinoma **

Polycystic liver disease Polycystic liver disease (PLD) usually describes the presence of multiple cysts scattered throughout normal liver tissue. PLD is commonly seen in association with autosomal-dominant polycystic kidney disease, with a prevalence of 1 in 400 to 1000, ...

Adrenal The adrenal glands (also known as suprarenal glands) are endocrine glands that produce a variety of hormones including adrenaline and the steroids aldosterone and cortisol. They are found above the kidneys. Each gland has an outer cortex whic ...

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 A renal cyst is a fluid collection in or on the kidney. There are several types based on the Bosniak classification. The majority are benign, simple cysts that can be monitored and not intervened upon. However, some are cancerous or are suspicio ...

(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 A colloid cyst is a non-malignant tumor in the brain. It consists of a gelatinous material contained within a membrane of epithelial tissue. It is almost always found just posterior to the foramen of Monro in the anterior aspect of the third ve ...

* Pineal gland cyst (in the pineal gland in the brain) *

Glial cyst Glia, also called glial cells (gliocytes) or neuroglia, are non-neuronal cells in the central nervous system (brain and spinal cord) and the peripheral nervous system that do not produce electrical impulses. They maintain homeostasis, form mye ...

Tarlov cyst Tarlov cysts, are type II innervated meningeal cysts, cerebrospinal-fluid-filled (CSF) sacs most frequently located in the spinal canal of the sacral region of the spinal cord ( S1– S5) and much less often in the cervical, thoracic or lumbar ...

(spinal canal)

Musculoskeletal system

Aneurysmal bone cyst Aneurysmal bone cyst (ABC) is a non-cancerous bone tumor composed of multiple varying sizes of spaces in a bone which are filled with blood. The term is a misnomer, as the lesion is neither an aneurysm nor a cyst. It generally presents with pai ...

, a benign bone tumor with a

radiographic Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical radiography ("diagnostic" and "therapeut ...

cystic appearance. * Baker's cyst or popliteal cyst (behind the knee joint) *

Mucoid cyst A myxoid cyst is a cutaneous condition often characterized by nail plate depression and grooves. See also * Scleroderma * List of cutaneous conditions * List of radiographic findings associated with cutaneous conditions Many conditions of ...

(ganglion cysts of the digits) * Stafne static bone cyst (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 bone ...

) * 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 hair ...

(seen in ovaries, testes, and many other locations, from head to tailbone) * Ganglion cyst (hand and foot joints and tendons) *

(ganglion cysts of the digits)

Infectious cysts

* Cysticercal cyst – an infection due to the larval stage of ''Taenia sp.'' (Crain's backs) *

– 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 Cesto ...

)

Neoplastic cysts

* Keratocystic odontogenic tumor *

Calcifying odontogenic cyst Calcifying odotogenic cyst (COC) is a rare developmental lesion that comes from odontogenic epithelium. It is also known as a calcifying cystic odontogenic tumor, which is a proliferation of odontogenic epithelium and scattered nest of ghost cel ...

Treatment

Treatment ranges from simple enucleation of the cyst to

curettage Curettage ( or ), in medical procedures, is the use of a curette (French, meaning scoop Mosby's Medical, Nursing & Allied Health Dictionary, Fourth Edition, Mosby-Year Book 1994, p. 422) to remove tissue by scraping or scooping. Curettages are ...

to resection. There are cysts—e.g.,

buccal bifurcation cyst Buccal bifurcation cyst is an inflammatory odontogenic cyst, of the paradental cysts family, that typically appears in the buccal bifurcation region of the mandibular first molars in the second half of the first decade of life. Infected 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 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 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 disorders ...

whose name is related to fibrosis of the

cystic duct The cystic duct is the short duct that joins the gallbladder to the common hepatic duct. It usually lies next to the cystic artery. It is of variable length. It contains ' spiral valves of Heister', which do not provide much resistance to the ...

(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, although ...

) 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 ente ...

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