| Teratomas are the most common ovarian
neoplasm constituting 20% of all ovarian tumors and about 95% of
germ cell tumors. These are common tumors in adolescent and young
women but may also occur in the elderly. Malignant teratomas are
rare (1% to 3% of cases). Between 10 and 15 percent of dermoids
are bilateral. Cystic teratomas are usually composed of three germ
cell layers: ectoderm, mesoderm, and endoderm, with ectoderm predominating.
they often contain fat, teeth (40% of dermoids contain teeth), hair
and bone fragments.
Cystic teratomas are commonly asymptomatic, although pain may
result in the event of torsion or rupture. Larger lesions may
produce an abdominal mass or swelling.
Sonographically, dermoids can range from totally anechoic to a
hyperechoic mass. Most commonly, they appear as complex masses.
The majority of dermoids are very echogenic and they may shadow.
Benign cystic teratomas characteristically show an anechoic cystic
component and a shadowing density that corresponds to a dermoid
plug. Strong acoustic attenuation occurs in the presence of bone,
teeth, and hair in the plug, sometimes producing the "tip-of-the-iceberg"
sign. This intensely echogenic focus is the cystic teratoma's
most defining feature. Other distinctive sonographic features
include a fat-fluid level and hyperechoic lines and dots generated
by hair. The size of the dermoid plug varies from a few mm to
that occupying the entire mass.
Color Doppler sonography may be helpful in differentiation of
benign and malignant cystic teratomas. Blood flow in benign cystic
teratomas is typically found only in the periphery because the
cyst contains mostly avascular fat and hair. Conversely, malignant
teratomas show intratumoral blood flow significantly more frequently
than benign teratomas, with the exception of struma ovarii, a
rare and typically benign form of cystic teratoma that contains
highly vascular thyroid tissue .
Benign cystic teratomas have variable appearances
that may mimic hemorrhagic cysts, endometriomas, primary ovarian
neoplasms, and metastatic tumors. Teratomas, however, often have
two or more features characteristic of dermoids, and sonographically
similar lesions usually have no more than one. Différential
* Haemorrhagic ovarian cyst.
* Fibroma and fibrothecoma.
* Granulosa cell tumour.
* Mucinous or serous cystadenomas or cystadenocarcinoma.
* Endometroid carcinoma.
* Adenocarcinoma without serous or mucous collection.
* Krukenberg's tumeurs.
* Lymphoma of ovaries.
Cystic teratomas are often surgically removed, but because of
their typically slow growth rate, patient fertility concerns may
be considered. Wherever possible, lesions are excised without
removal of the involved ovary; in fact, surgery can sometimes
be delayed until patients have completed their families.
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