A dermoid cyst is a teratoma of a

cyst 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 ...

ic nature that contains an array of developmentally mature, solid tissues. It frequently consists of

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other cuticle, animal coverings, such as the arthropod exoskeleton, have diffe ...

, hair follicles, and sweat glands, while other commonly found components include clumps of long hair, pockets of

sebum A sebaceous gland is a microscopic exocrine gland in the skin that opens into a hair follicle to secrete an oily or waxy matter, called sebum, which lubricates the hair and skin of mammals. In humans, sebaceous glands occur in the greatest nu ...

blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in th ...

, fat,

bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, an ...

, nail,

teeth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, te ...

eyes Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and c ...

, cartilage, and

thyroid The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans it is in the neck and consists of two connected lobes. The lower two thirds of the lobes are connected by a thin band of tissue called the thyroid isthmus. The t ...

tissue. As dermoid cysts grow slowly and contain mature tissue, this type of cystic teratoma is nearly always benign. In those rare cases wherein the dermoid cyst is

malignant 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 ...

, a

squamous cell carcinoma Squamous-cell carcinomas (SCCs), also known as epidermoid carcinomas, comprise a number of different types of cancer that begin in squamous cells. These cells form on the surface of the skin, on the lining of hollow organs in the body, and on th ...

usually develops in adults, while infants and children usually present with an endodermal sinus tumor.Freedberg, et al. (2003). ''Fitzpatrick's Dermatology in General Medicine''. (6th ed.). McGraw-Hill. .

Location

Due to its classification, a dermoid cyst can occur wherever a teratoma can occur.

Vaginal and ovarian dermoid cysts

Ovaries normally grow cyst-like structures called follicles each month. Once an egg is released from its follicle during

ovulation Ovulation is the release of eggs from the ovaries. In women, this event occurs when the ovarian follicles rupture and release the secondary oocyte ovarian cells. After ovulation, during the luteal phase, the egg will be available to be fertilize ...

, follicles typically deflate. Sometimes fluid accumulates inside the follicle, forming a simple (containing only fluid) cyst. The majority of these functional cysts resolve spontaneously. While all ovarian cysts can range in size from very small to quite large, dermoid cysts are not classified as functional cysts. Dermoid cysts originate from pluripotent

germ cells Germ or germs may refer to: Science * Germ (microorganism), an informal word for a pathogen * Germ cell, cell that gives rise to the gametes of an organism that reproduces sexually * Germ layer, a primary layer of cells that forms during embry ...

(which are present at birth) that differentiate abnormally, developing characteristics of mature dermal cells. Complications exist, such as torsion (twisting), rupture, and infection, although their incidence is rare. Dermoid ovarian cysts which are larger present complications which might require removal by either

laparoscopy Laparoscopy () is an operation performed in the abdomen or pelvis using small incisions (usually 0.5–1.5 cm) with the aid of a camera. The laparoscope aids diagnosis or therapeutic interventions with a few small cuts in the abdomen.Medl ...

or laparotomy (traditional surgery). Rarely, a dermoid cyst can develop in the vagina. File:Large ovarian cyst.JPG, Large ovarian cyst File:Dermoid cyst.jpg, Dermoid cyst in

vaginal ultrasonography Vaginal ultrasonography is a medical ultrasonography that applies an ultrasound transducer (or "probe") in the vagina to visualize organs within the pelvic cavity. It is also called transvaginal ultrasonography because the ultrasound waves go ''a ...

File:ComplexCystofaDermoid.png, A complex cyst due to a dermoid as seen on ultrasound File:DermoidCyst(CT)Mark.png, A complex cyst due to a dermoid as seen on CT. Arrow points to bone or teeth.

Periorbital dermoid cysts

Dermoid cysts can appear in young children, often near the lateral aspect of the eyebrow (right part of the right eyebrow or left part of the left eyebrow). Depending on the perceived amount of risk, these are sometimes excised or simply kept under observation. An inflammatory reaction can occur if a dermoid cyst is disrupted, and the cyst can recur if it is not completely excised. Sometimes complete excision is not practical if the cyst is in a dumbbell configuration, whereby it extends through a suture line in the skull. If dermoid cysts appear on the medial aspect, the possibility of an

encephalocele Encephalocele is a neural tube defect characterized by sac-like protrusions of the brain and the membranes that cover it through openings in the skull. These defects are caused by failure of the neural tube to close completely during fetal develop ...

becomes greater and should be considered among the differential diagnoses. Other areas where a dermoid cyst may appear are the

brain The brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head ( cephalization), usually near organs for special ...

scrotum The scrotum or scrotal sac is an anatomical male reproductive structure located at the base of the penis that consists of a suspended dual-chambered sac of skin and smooth muscle. It is present in most terrestrial male mammals. The scrotum co ...

and the

pharynx The pharynx (plural: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the oesophagus and trachea (the tubes going down to the stomach and the lungs). It is found in vertebrates and invertebrates, though its ...

. Dermoid cysts develop during pregnancy. They occur when skin cells and things like hair, sweat glands, oil glands or fatty tissue get trapped in the skin as a baby grows in the womb. Dermoid cysts are present at birth (congenital) and are common. It can be months or years before a dermoid cyst is noticed on a child because the cysts grow slowly. Dermoid cyst symptoms are minor and the cysts are usually painless. They are not harmful to a child's health. If they become infected, the infection must be treated and the cyst should be removed. It is easier to remove cysts and prevent scars if the cyst is removed before it gets infected.

Spinal dermoid cysts

Spinal dermoid cysts are benign ectopic growths thought to be a consequence of embryology errors during

neural tube In the developing chordate (including vertebrates), the neural tube is the embryonic precursor to the central nervous system, which is made up of the brain and spinal cord. The neural groove gradually deepens as the neural fold become elevated, ...

closure. Their reported incidence is extremely rare, accounting for less than 1% of intramedullary

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 ...

tumours. It has been proposed that a possible 180 cases of spinal dermoid tumours have been identified over the past century in the literature. Dermoid cysts more often involve the lumbosacral region than the

thoracic vertebrae In vertebrates, thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. In humans, there are twelve thoracic vertebrae and they are intermediate in size between the cervical ...

and are extramedullary presenting in the first decade of life. Various hypotheses have been advanced to explain the pathogenesis of spinal dermoids, the origin of which may be acquired or congenital. * Acquired or iatrogenic dermoids may arise from the implantation of epidermal tissue into the subdural space i.e. spinal cutaneous inclusion, during needle puncture (e.g. lumbar puncture) or during surgical procedures on closure of a dysraphic malformation. * Congenital dermoids, however, are thought to arise from cells whose position is correct but which fail to differentiate into the correct cell-type. The long-time held belief was that the inclusion of cutaneous ectodermal cells occurred early in embryonic life, and the displaced pluripotent cells developed into a dermoid lesion. Spinal abnormalities, e.g. intramedullary dermoid cysts may arise more frequently in the lumbosacral region (quite often at the level of the

conus medullaris ''Conus'' is a genus of predatory sea snails, or cone snails, marine gastropod mollusks in the family Conidae.Bouchet, P.; Gofas, S. (2015). Conus Linnaeus, 1758. In: MolluscaBase (2015). Accessed through: World Register of Marine Species ...

) and may be seen with other congenital anomalies of the spine including posterior

spina bifida Spina bifida (Latin for 'split spine'; SB) is a birth defect in which there is incomplete closing of the spine and the membranes around the spinal cord during early development in pregnancy. There are three main types: spina bifida occulta, m ...

occulta as identified by the neuroradiological analysis.

Diagnosis

Differential diagnosis

A small dermoid cyst on the coccyx can be difficult to distinguish from a pilonidal cyst. This is partly because both can be full of hair. A pilonidal cyst is a pilonidal sinus that is obstructed. Any teratoma near the body surface may develop a sinus or a fistula, or even a cluster of these. Such is the case of Canadian Football League linebacker Tyrone Jones, whose teratoma was discovered when he blew a tooth out of his nose.

Treatment

Treatment for dermoid cyst is complete surgical removal, preferably in one piece and without any spillage of cyst contents. Marsupialization, a surgical technique often used to treat pilonidal cyst, is inappropriate for dermoid cyst due to the risk of malignancy. The association of dermoid cysts with pregnancy has been increasingly reported. They usually present the dilemma of weighing the risks of surgery and anesthesia versus the risks of untreated adnexal mass. Most references state that it is more feasible to treat bilateral dermoid cysts of the ovaries discovered during pregnancy if they grow beyond 6 cm in diameter.

References

External links

{{DEFAULTSORT:Dermoid Cyst Cutaneous congenital anomalies Gynaecologic disorders Germ cell neoplasia Eye diseases