an abnormal closed epithelium-lined sac in the body that contains a liquid or semisolid substance. Most are harmless, but they should be removed when possible because they occasionally may change into malignant growths, become infected, or obstruct a gland. There are four main types of cysts: retention cysts
, exudation cysts
, embryonic cysts
, and parasitic cysts
3. a stage in the life cycle of certain parasites, during which they are enveloped in a protective wall.
alveolar c's dilatations of pulmonary alveoli, which may fuse by breakdown of their septa to form large air cysts (pneumatoceles).
a fluid-filled cyst between the layers of the leptomeninges
, lined with arachnoid membrane, usually in the sylvian fissure.
Baker cyst a swelling on the back of the knee, due to escape of synovial fluid that has become enclosed in a sac of membrane.
Bartholin cyst a mucus-filled cyst of a Bartholin gland, usually developing as a consequence of an obstruction of the duct by trauma, infection, epithelial hyperplasia, or congenital atresia or narrowing.
Blessig c's cystic spaces formed at the periphery of the retina.
blue dome cyst 2.
a cyst due to endometriosis
, found in healed wounds such as those of an episiotomy or an incision for a cesarean section; it is usually found in the vaginal fornix or on the cervix.
Boyer cyst an enlargement of the subhyoid bursa.
) (branchiogenous cyst
) see branchial cyst
bronchogenic cyst a congenital cyst, usually in the mediastinum or lung, arising from anomalous budding during formation of the tracheobronchial tree, lined with bronchial epithelium that may contain secretory elements.
chocolate cyst one filled with hemosiderin, causing a dark color, following local hemorrhage, such as may occur in the ovary in ovarian endometriosis.
choledochal cyst a congenital cystic dilatation of the common bile duct, which may cause pain in the right upper quadrant, jaundice, fever, or vomiting, or be asymptomatic.
daughter cyst a small parasitic cyst developed from the walls of a larger cyst.
an odontogenic cyst
surrounding the crown of a tooth, originating after the crown is completely formed.
duplication cyst a congenital cystic malformation of the alimentary tract, consisting of a duplication of the segment to which it is adjacent, occurring anywhere from the mouth to the anus but most frequently affecting the ileum and esophagus.
one developing from bits of embryonic tissue that have been overgrown by other tissues, or from developing organs that normally disappear before birth. An example is a branchial cyst
) a cyst of the intestine arising or developing from some fold or pouch along the intestinal tract. Called also enterocyst
) an intradermal or subcutaneous cyst containing keratinizing squamous epithelium; it arises from occluded hair follicles. Called also wen
epidermal inclusion cyst
a type of epidermal cyst
occurring on the head, neck, or trunk, formed by keratinizing squamous epithelium with a granular layer.
1. any cyst lined by keratinizing stratified squamous epithelium, found most often in the skin.
exudation cyst a cyst formed by the slow seepage of an exudate into a closed cavity.
follicular cyst one due to occlusion of the duct of a follicle or small gland, especially one formed by enlargement of a graafian follicle as a result of accumulated transudate.
the larval stage of the tapeworms Echinococcus granulosis
and E. multilocularis
; each one contains daughter cysts that have many scoleces (mouths). See also hydatid disease
. Called also echinococcus cyst
inclusion cyst one formed by the inclusion of a small portion of epithelium or mesothelium within connective tissue along a line of fusion of embryonic processes; several types are found in the oral and nasal regions.
keratinizing cyst one arising in the pilosebaceous apparatus, lined by stratified squamous epithelium and containing largely macerated keratin and often sufficient sebum to render the contents greasy or rancid.
mucus retention cyst
a mucus-containing retention cyst
caused by blockage of a salivary gland duct.
1. a cyst containing several loculi or spaces.
a hydatid cyst
with many small irregular cavities that may contain scoleces but generally little fluid.
3. a thick-walled cyst in the kidney, found in clusters and usually unilaterally. In children it contains blastema and may develop into a Wilms tumor.
myxoid cyst a nodular lesion usually overlying a distal interphalangeal finger joint in the dorsolateral or dorsomesial position, consisting of focal mucinous degeneration of the collagen of the dermis; not a true cyst, lacking an epithelial wall, it does not communicate with the underlying synovial space.
Naboth's c's (nabothian c's) cysts that occur when mucus-producing glands in the columnar epithelium of the uterine cervix become covered over by squamous epithelium resulting from metaplasia; they are usually found in the transformation zone of the cervix. Called also Naboth's or nabothian follicles.
nasoalveolar cyst (nasolabial cyst) a fissural cyst arising outside the bones at the junction of the globular portion of the medial nasal process, lateral nasal process, and maxillary process.
one derived from epithelium, usually containing fluid or semisolid material, which develops during various stages of odontogenesis
; nearly always enclosed within bone.
one forming around larval parasites (tapeworms, amebas, trichinae), such as a hydatid cyst
perineurial cyst an outpouching of the perineurial space on the extradural portion of the posterior sacral or coccygeal nerve roots at the junction of the root and ganglion; it may cause low back pain and sciatica.
one in the periodontal ligament and adjacent structures, usually at the apex of the tooth (periapical cyst
a type of epidermal cyst
, almost always found on the scalp, arising from the outer root sheath of the hair follicle.
radicular cyst an epithelium-lined sac at the apex of a tooth.
(Rathke's cleft c's
) groups of epithelial cells forming small colloid-filled cysts in the pars intermedia of the pituitary gland; they are vestiges of Rathke's pouch
and are closely related to craniopharyngiomas
retention cyst a tumorlike accumulation of a secretion formed when the outlet of a secreting gland is obstructed. These cysts may develop in any of the secretory glands, such as the breast, pancreas, kidney, salivary or sebaceous glands, or mucous membranes.
solitary bone cyst a pathologic bone space in the metaphyses of long bones of growing children; it may be either empty or filled with fluid and have a delicate connective tissue lining.
subchondral cyst a bone cyst within the fused epiphysis beneath the articular plate.
1. one resulting from hemorrhage into a corpus luteum.
2. a bloody cyst resulting from endometriosis.
theca-lutein cyst a cyst of the ovary in which the cystic cavity is lined with theca cells.
traumatic bone cyst a cavity (not a true cyst) formed in bone, particularly the mandible, in response to trauma. The hematoma precipitated by trauma is resorbed but bone is not replaced; the space formed is usually empty and lacks an epithelial lining.
a cyst of the broad ligament developed from vestiges of the mesonephros
Patient discussion about arachnoid cyst
Q. What is the treatment for an arachnoid cyst? My 15 year old son has just been diagnosed with an arachnoid cyst. What is the treatment? Is an operation necessary?
A. An operation is not always necessary, it depends on the size and location of the cyst. I suggest you take your son to a neurologist or a neurosurgeon for further consult.
Q. Is there any problem, if an arachnoid cyst ,2cmx1.5cm size, rostral to cerebellar region left untreated? symptoms: repeated headaches, twitching of muscles, tiredness
A. An arachnoid cyst that leads to symptoms usually needs treatment. Mild symptoms as you suggested are ok to left untreated however gradual onset of new symptoms may arise such as seizures, paralysis and other complications, therefore once symptoms occur one should consider treatment.
Q. info on arachnoid cyst in the right posterior fossa
A. Basically it's like a small sac filled with fluid. The problem is that the skull is a rigid closed space, which means that if there's something other than the brain, it'll occupy space, usually on expense of the brains' space. These kinds of problems are often referred to as "space occupying lesion".More discussions about arachnoid cyst
It's usually congenital (i.e. develops during pregnancy), and even when it cause symptoms they develop slowly.
YOu can read more here (http://en.wikipedia.org/wiki/Arachnoid_cyst)