Ovarian teratomas
- Lesion
A teratoma grows hair, skin, teeth and even brain. The mature cyst is benign; the immature one, of young girls, is a cancer graded by its brain tissue.
What it is
Teratomas are germ cell tumours that differentiate into tissues of more than one germ layer. The mature cystic teratoma (dermoid cyst) is the most common ovarian tumour of young women: a benign cyst lined by skin with hair, sebum, teeth and other mature tissues. Immature teratoma, of children and young women, contains embryonal-type tissue, mostly primitive neuroepithelium, and is malignant. Monodermal teratomas are made of a single tissue, such as thyroid (struma ovarii) or neuroendocrine cells (carcinoid), and can cause hormone syndromes.
Structure
- Dermoid cyst wall: keratinizing squamous epithelium with hair follicles and sebaceous and sweat glands; beneath it any mature tissue may appear.
- Rupture of contents provokes foreign-body granulomas.
- Immature teratoma: fleshy, solid, haemorrhagic mass; primitive neuroepithelium among other immature and mature tissues.
- Struma ovarii: brown solid tissue of thyroid follicles with colloid.
Step by step
- A germ cell completes the first meiotic division and then begins to divide on its own (parthenogenetic origin).
- Its descendants differentiate along ectodermal, mesodermal and endodermal lines.
- Fully differentiated tissues form a benign mature teratoma; persisting embryonal tissue makes an immature teratoma.
- Rarely, one tissue in a mature teratoma becomes malignant, or neural tissue triggers autoimmunity against NMDA receptors.
Clinical notes
- Mature teratomas are often incidental; they are a leading cause of ovarian torsion in young women.
- A young woman with psychiatric symptoms, seizures and dyskinesias should be checked for an ovarian teratoma; removing it improves anti-NMDA receptor encephalitis.
- Immature teratomas are treated with surgery and, for higher grades, chemotherapy; prognosis depends on grade and stage.
Test yourself
Think of the answer, then tap the question to see it.
What is the karyotype and origin of a mature cystic teratoma?
Usually 46,XX; it arises from a germ cell after the first meiotic division.
Which tissue grades an immature teratoma?
The amount of immature (primitive) neuroepithelium.
Which autoimmune encephalitis is associated with ovarian teratoma?
Anti-NMDA receptor encephalitis, triggered by neural tissue in the teratoma.
What is struma ovarii?
A monodermal teratoma composed mostly of thyroid tissue, which can cause hyperthyroidism.
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Ovarian Germ Cell Tumors Treatment (PDQ®)–Health Professional Version (National Cancer Institute, 2026); Ovarian Torsion (StatPearls (NCBI Bookshelf), 2026).
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Representative model, for educational purposes only.