Ovarian germ cell tumours and mature teratoma
Ovarian germ cell tumours grow from the egg-forming cell line; the mature teratoma (dermoid cyst), which can contain several tissue types, is the best-known usually benign example.
Remember
Ovarian germ cell tumours come from the egg-forming cell line and usually affect women under 30, and the mature teratoma (dermoid cyst) is the usually benign example.
Memory aid
Mature means grown-up tissue in a usually benign cyst, whereas immature means unfinished tissue in a malignant tumour
Use the words mature and immature to tell the usually benign dermoid cyst from the malignant immature teratoma.
Ovarian tumours are classified by the cell they come from. Germ cells are the cells that form eggs (ova), so a germ cell tumour grows from this egg-forming line, either from egg cells or from the immature cells that form them.
These tumours can be benign or malignant. They occur most commonly before the age of 30, so they are tumours of younger women. Epithelial cancers, which arise from the cells lining the ovary and fallopian tube, mainly affect women around and after the menopause. Granulosa and theca cells, which support the egg, give rise to sex cord stromal tumours (tumours of the supporting cells), some of which make hormones.
The mature teratoma is the best-known benign subtype, and it is often called a dermoid cyst. Germ cells can develop into many different tissue types, so the tumour may contain structures such as skin, hair and teeth (dermoid means skin-like). The word mature refers to the well-developed tissue seen under the microscope, and this is the usually benign member of the group.
Most mature teratomas cause no symptoms, but they can twist on their blood supply (torsion), which causes sudden severe pain, or they can rupture. Malignant change is uncommon, occurring in roughly 1 to 3% of cases.
The malignant germ cell tumours include immature teratomas, dysgerminomas, yolk sac tumours and choriocarcinomas (tumours derived from placental-type cells). An immature teratoma is malignant and contains primitive, undeveloped tissue.
Key facts
- Origin
- Ovarian germ cell tumours arise from the egg-forming cell line, from egg cells or from the immature cells that form them.
- Behaviour
- They can be benign or malignant.
- Age
- They occur most commonly before the age of 30.
- Mature teratoma
- Also called a dermoid cyst, a germ cell tumour that is usually benign and can contain tissues such as skin, hair and teeth.
- Complications
- In a mature teratoma, torsion (twisting of the ovary), rupture and, rarely, malignant transformation.
- Malignant types
- Malignant germ cell tumours include immature teratoma, dysgerminoma, yolk sac tumour and choriocarcinoma.
- Contrast
- Epithelial ovarian cancer mainly affects women around and after the menopause.
Exam traps
- An immature teratoma is not the usually benign dermoid cyst, because it contains primitive, undeveloped tissue and is a malignant tumour.
- Arising from the egg cells does not make a germ cell tumour malignant: these tumours can be benign or malignant, and the mature teratoma (dermoid cyst) is a common benign example.
- Germ cell tumours do not follow the age pattern of epithelial cancers: they usually occur before the age of 30, whereas it is epithelial cancers that mainly affect women around and after the menopause.
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