| ovary, dermoid cyst of the | Tumour that develops from a totipotential germ cell (a primary oocyte) retained within the egg sac (ovary). Being totipotential, that cell can give rise to all orders of cells necessary to form mature tissues and often recognizable structures such as hair, bone and sebaceous (oily) material, neural tissue and teeth. Dermoid cysts may occur at any age but the prime age of detection is in the childbearing years. The average age is 30. Up to 15% of women with ovarian teratomas have them in both ovaries. Dermoid cysts can range in size from a centimeter (less than a half inch) up to 45 cm (17 inches) in diameter. They can cause the ovary to twist (torsion) and imperil its blood supply. Although the large majority (about 98%) of ovarian teratomas are benign, the remaining fraction (about 2%) becomes cancerous (malignant). The larger the dermoid, the greater the risk of rupture with spillage of the greasy contents which can create problems with adhesions, pain etc. Removal is usually the treatment of choice by laparotomy (surgery) or laparoscopy (with a scope). Dermoid cysts of the ovary are also called simply dermoids or ovarian teratomas. (12 Dec 1998) |
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| Tarlov's cyst | A perineural cyst found in the proximal radicles of the lower spinal cord; it is usually productive of symptoms. (05 Mar 2000) |
| tarry cyst | A cyst or collection of old blood having a tarry or black, sticky appearance; usually due to endometriosis. (05 Mar 2000) |
| tarsal cyst | Also called a Meibomian cyst or a chalazian. A tarsal cyst is an inflammation of the oil gland of the eyelid. (12 Dec 1998) |
| teratomatous cyst | A cyst containing structures derived from all three of the primary germ layers of the embryo. (05 Mar 2000) |
| ear cyst | A sebaceous cyst that occurs most commonly in the ear canal. They are bulging sac-like collections of dead skin cells and fluid. These cysts can be quite painful and may block the canal causing hearing loss. Treatment may include warm wet compresses, antibiotics (if infected) and surgical removal in some cases. Most resolve spontaneously. (27 Sep 1997) |
| echinococcus cyst | A cyst formed in the liver, or, less frequently, elsewhere, by the larval stage of Echinococcus, chiefly in ruminants; two morphological forms caused by Echinococcus granulosus are found in humans: the unilocular hydatid cyst and the osseous hydatid cyst; a third form in humans is the alveolar hydatid cyst, caused by Echinococcus multilocularis. Synonym: echinococcus cyst, hydatid. (05 Mar 2000) |
| thyroglossal cyst | <anatomy, embryology> A thyroglossal cyst is a fluid-filled sac that is present at birth and located in the midline of the neck. A thyroglossal cyst is a result of incomplete closure of a segent of a tube-like structure (the thyroglossal duct) that is present, and normally closes, as the embryo develops. Synonym: thyrolingual cyst. (07 Mar 2000) |
| thyroglossal duct cyst | A cyst in the midline of the neck resulting from nonclosure of a segment of the ductus thyroglossus. Synonym: cervical cyst. (05 Mar 2000) |
| thyrolingual cyst | A thyrolingual cyst is a fluid-filled sac that is present at birth and located in the midline of the neck. A thyrolingual cyst is a result of incomplete closure of a segent of a tube-like structure (the thyrolingual duct) that is present, and normally closes, as the embryo develops. A thyrolingual cyst is also called a thyroglossal cyst. (12 Dec 1998) |
| Tornwaldt's cyst | <anatomy> A cystic notochordal remnant found inconstantly in the posterior wall of the nasopharynx at the lower end of the pharyngeal tonsil. Synonym: bursa pharyngea, Luschka's bursa, Tornwaldt's cyst. (05 Mar 2000) |
| endometrial cyst | A cyst resulting from endometrial implantation outside the uterus, as in endometriosis. (05 Mar 2000) |
| endothelial cyst | A serous cyst whose sac is lined with endothelium. (05 Mar 2000) |
| traumatic bone cyst | A unilocular cyst containing serous fluid and lined with a thin layer of connective tissue, occurring usually in the shaft of a long bone in a child. Synonym: idiopathic bone cavity, osteocystoma, simple bone cyst, traumatic bone cyst, unicameral bone cyst. (05 Mar 2000) |
| ependymal cyst | A circumscribed distention of some portion of the central canal of the spinal cord or of the cerebral ventricles. Synonym: neural cyst. (05 Mar 2000) |