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
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
cyst (sist) [Gr. kystis, bladder, sac]
1. A closed sac or pouch with a definite wall, containing fluid, semifluid, or solid material. It is usually an abnormal structure resulting from developmental anomalies, obstruction of ducts, or parasitic infection.
2. In biology, a structure formed by and enclosing certain organisms in which they become inactive, such as the cyst of certain protozoans or of the metacercariae of flukes.
A cyst formed around a foreign body.
Dilation and rupture of pulmonary alveoli to form air cysts.
A cyst near the apex of the root of a nonvital tooth.
An abnormal collection of cerebrospinal fluid within the arachnoid membrane. The cysts may compress nearby structures within the brain. In infants, they may cause headaches, altered mental status, learning disabilities, or enlargement of the head. In adults, they are an occasional cause of epilepsy.
Baker cyst See: Baker cyst.
Bartholin cyst See: Bartholin, Caspar (the younger)
blue dome cyst
1. A mammary cyst containing light, straw-colored fluid, which appears blue when seen through the surrounding tissue.
2. A small dark-blue cyst in the vagina caused by retained menstrual blood seen in endometriosis.
branchial cystCervical cyst.
A cystic mass in bone, usually a normal variant or a benign tumor.
Boyer cyst See: Boyer cyst
A closed epithelial sac derived from a branchial groove of its corresponding pharyngeal pouch. Synonym: branchial cyst
An ovarian cyst with darkly pigmented gelatinous contents.
A cyst with gelatinous contents.
A cyst that consists of solid material and fluid-filled cavities; it may have walls of tissue inside it or internal echoes. When a complex cyst is identified on ultrasound, surgical removal is generally indicated to exclude malignancy.
A cyst present at birth and resulting from abnormal development, such as a dermoid cyst, imperfect closure of a structure as in spina bifida cystica, or nonclosure of embryonic clefts, ducts, or tubules, such as cervical cysts.
A cyst growing out of the walls of another cyst.
A cyst that forms from any of the odontogenic tissues.
A fluid-filled, epithelial-lined cyst usually surrounding the crown of a tooth that is erupting or has not yet erupted. The tooth normally erupts through the cyst without treatment. Synonym: eruption cyst
; follicular cyst
; follicular odontoma
1. An ovarian teratoma.
2. A nonmalignant cystic tumor containing elements derived from the ectoderm, such as hair, teeth, or skin. These tumors occur frequently in the ovary but may develop in other organs such as the lungs.
A cyst formed in a natural enclosed cavity, such as a follicular cyst of the ovary.
echinococcus cystHydatid cyst.
An ovarian cyst or tumor lined with endometrial tissue, usually seen in ovarian endometriosis.
A cyst filled with keratin, sebum, and skin debris that may form on the scalp, the back of the neck, or the axilla. It is benign andf can be removed surgically. Synonym: sebaceous cyst
eruption cystDentigerous cyst.
A cyst arising from hemorrhage or escape of other body fluids into tissues.
A cyst caused by trapping of an exudate in a closed area.
FOLLICULAR CYST: Follicular cysts seen on ultrasonography of the thyroid gland.
A cyst arising from a follicle, as a follicular cyst of the thyroid gland, the ovary, or a forming tooth. Synonym: dentigerous cyst
ganglion cystganglion (2)
Gartner cyst See: Gartner cyst
Gorlin cyst See: Gorlin cyst
A cyst formed by the growth of the larval form of Echinococcus granulosus, usually in the liver. Synonym: echinococcus cyst
A cyst resulting from displacement of portions of the epidermis, as may occur in injuries.
A cystic formation between the layers of the broad ligament.
A cyst occurring in the normal involution of an organ or structure, as in the mammary gland.
A cyst containing keratin.
cysts of liver
Simple cysts, usually small and single; or hydatid cysts; or cysts associated with cystic disease of the liver, a rare condition usually associated with congenital cystic kidneys. See: Echinococcus granulosus
A fluid-filled cyst often associated with a degenerative horizontal meniscal tear, more frequently seen in the lateral meniscus of the knee. This ganglion-like cyst may present with a palpable mass at the joint line of the knee and can be visualized by magnetic resonance imaging.
morgagnian cyst See: Morgagni, Giovanni B
Morgagni cyst See: Morgagni, Giovanni B
A hydatid cyst enveloping smaller ones.
A retention cyst composed of mucus.
A cyst caused by closure of the ducts of the nabothian glands in the uterine cervix as a result of chronic cervicitis.
A cyst associated with the teeth, such as a dentigerous or radicular cyst.
A fluid-filled cyst that develops in the ovary and consists of one or more chambers. The main types of cysts are follicular cysts, the corpus luteum, teratoma, and endometrioma. The patient's primary complaint is generally pelvic pain or pain during intercourse. The cysts may be palpated during bimanual examination but are diagnosed by ultrasound. Many cysts resolve spontaneously. Although nonmalignant, the cyst may have to be removed surgically because of twisting of the pedicle, which causes gangrene, or because of pressure. See: polycystic ovary syndrome
A cyst enclosing the larval form of certain parasites, such as the cysticercus or hydatid of tapeworms or the larva of certain nematodes, i.e., Trichinella.
A cyst of the parovarium.
periapical cystRadicular cyst.
An epithelial cyst with a wall that resembles the follicular epithelium. It is filled with a homogeneous mixture of keratin and lipid. Synonym: trichilemma cyst
A cyst most often in the sacrococcygeal region, usually at the upper end of the intergluteal cleft. It is due to a developmental defect that permits epithelial tissue to be trapped below the skin or may be acquired. This type of cyst may become symptomatic in early adulthood when an infected draining sinus forms. Synonym: pilonidal fistula
popliteal cystBaker cyst.
An anomalous cavity of the brain that communicates with the ventricular system.
A cyst lined with epithelium that proliferates, forming projections that extend into the cavity of the cyst.
A necrotic, inflammatory cyst that develops at the root of a nonvital tooth. The cyst is attached to the root of the tooth and may be lateral to it if the cyst is associated with a lateral pulp canal. Synonym: periapical cyst; root-end cyst
A cyst retaining the secretion of a gland, as in a mucous or sebaceous cyst.
root-end cystRadicular cyst.
sebaceous cystEpidermoid cyst.
A cyst of the epididymis, ductus deferens, or other sperm-carrying ducts that contain semen.
A cyst of the hypophyseal stalk just above the floor of the sella turcica. Its wall is frequently calcified or ossified.
Accumulation of synovia in a bursa, synovial crypt, or sac of a synovial hernia, causing a tumor.
Benign enlargement of the Graafian follicle, typically occurring in pregnancies (particularly in multiple pregnancies) or in other conditions that cause markedly elevated levels of serum human chorionic gonadotropin (HCG) levels, e.g., molar pregnancies or choriocarcinomas. Synonym: hyperreactio luteinalis
trichilemma cystPilar cyst.
An ovarian cyst that ruptures into the lumen of an adherent uterine tube.
A cyst containing only one cavity.
A cyst in the vagina.
A congenital cyst of the gastrointestinal canal. Lined with ciliated epithelium, it is the remains of the omphalomesenteric duct.
A cyst lying in one of the broad ligaments of the uterus.illustration
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