Ovarian dermoid cyst and mature cystic teratoma are terms often used interchangeably to refer to the most common ovarian neoplasm. These slow-growing tumours contain elements from multiple germ cell layers and are best assessed with ultrasound.
Although they have very similar imaging appearances, the two have a fundamental histological difference: dermoids are composed only of dermal and epidermal elements, whereas teratomas have mesodermal and endodermal elements.
For the sake of simplicity both are discussed in this article, as much of the literature combines the two entities.
Mature cystic teratomas account for ~15% (range 10-20%) of all ovarian neoplasms. They tend to be identified in young women, typically around the age of 30 years 1 and are also the most common ovarian neoplasm in patients younger than 20 years 8.
Uncomplicated ovarian dermoids tend to be asymptomatic and are often discovered incidentally. They do however predispose to ovarian torsion, and may then present with acute pelvic pain.
Mature cystic teratomas are encapsulated tumours with mature tissue or organ components. They are composed of well-differentiated derivations from at least two of the three germ cell layers (i.e. ectoderm, mesoderm, and endoderm). They therefore contain developmentally mature skin complete with hair follicles and sweat glands, sometimes luxuriant clumps of long hair, and often pockets of sebum, blood, fat, bone, nails, teeth, eyes, cartilage, and thyroid tissue. Typically their diameter is smaller than 10 cm, and rarely more than 15 cm. Real organoid structures (teeth, fragments of bone) may be present in ~30% of cases.
They can be bilateral in 10-15% of cases 1-2.
- struma ovarii tumour: contains thyroid elements, however sometimes these are separately classified as specialised teratomas of the ovaries
May show calcific and tooth components with the pelvis.
Ultrasound is the preferred imaging modality. Typically an ovarian dermoid is seen as a cystic adnexal mass with some mural components. Most lesions are unilocular.
The spectrum of sonographic features includes:
- Rokitansky nodule: dermoid plug
- diffusely or partially echogenic mass with posterior sound attenuation owing to sebaceous material and hair within the cyst cavity (echogenic interface at edge of mass that obscures deep structures): the tip of the iceberg sign
- echogenic, shadowing calcific or dental (tooth) components
- presence of fluid-fluid levels 5
- multiple thin, echogenic bands caused by hair in the cyst cavity: the dot-dash pattern
CT has high sensitivity in the diagnosis of cystic teratomas 6, though is not routinely recommended for this purpose in view of ionising radiation.
Typically CT images demonstrate fat (areas with very low Hounsfield values), fat fluid level, calcification (sometimes tooth), Rokitansky protuberance and tufts of hair. The presence of most of the above tissues is diagnostic of ovarian cystic teratomas in 98% of cases 5. Whenever the size exceeds 10cms or soft tissue plugs and cauliflower appearance with irregular borders is seen, malignant transformation should be suspected 5.
When ruptured, the characteristic hypo-attenuating fatty fluid can be found as ante-dependent pockets, typically below the right hemidiaphragm, a pathognomonic finding 2. The escaped cyst content also leads to a chemical peritonitis and the mesentery may be stranded and the peritoneum thickened, which may mimic peritoneal carcinomatosis 2.
MR evaluation usually tends tend to be reserved for difficult cases, but is exquisitely sensitive to fat components. Both fat suppression techniques and chemical shift artefact can be used to confirm presence of fat.
Enhancement is also able identify solid invasive components, and as such can be used to accurately locally stage malignant variants.
Treatment and prognosis
They are slow growing (1-2 mm a year) and therefore some advocate non-surgical management. Larger lesions are often surgically removed. Many recommend initial serial follow for lesions under 7 cm to monitor growth, beyond which a resection is advised.
Recognised complications include:
- ovarian torsion: ~3-16% of ovarian teratomas on general: considered the most common complication
- rupture: ~1-4%
- malignant transformation: ~1-2%, usually into squamous cell carcinoma (adults) or rarely into endodermal sinus tumours (paediatrics)
- superimposed infection: 1%
- autoimmune haemolytic anaemia: <1%.
General differential imaging considerations include:
- haemorrhagic ovarian cyst
- pedunculated lipoleiomyoma of the uterus
ovarian cancer/ovarian serous or mucinous cystadenoma/cystadenocarcinoma
- this is usually only a serious consideration if typical features of mature cystic teratoma are absent (i.e. fat is absent)
- tend to occur in an older age group than dermoid cysts
Germ cell tumours
germ cell tumours
- general discussion
- germ cell tumours by location
- gonadal germ cell tumours
- ovarian germ cell tumour
- ovarian dysgerminoma
- non-seminomatous germ cell tumours
- ovarian embryonal cell carcinoma
- ovarian yolk sac tumour
- ovarian choriocarcinoma
- ovarian mixed germ cell tumour
- ovarian teratoma
- testicular germ cell tumour
- ovarian germ cell tumour
intracranial germ cell tumours
- intracranial germinoma
- non-germinomatous germ cell tumours
mediastinal germ cell tumours
- mediastinal germinoma
- mediastinal non-germinomatous germ cell tumours
- gonadal germ cell tumours
- 1. Outwater EK, Siegelman ES, Hunt JL. Ovarian teratomas: tumor types and imaging characteristics. Radiographics. 21 (2): 475-90. Radiographics (full text) - Pubmed citation
- 2. Fibus TF. Intraperitoneal rupture of a benign cystic ovarian teratoma: findings at CT and MR imaging. AJR Am J Roentgenol. 2000;174 (1): 261-2. AJR Am J Roentgenol (full text) - Pubmed citation
- 3. Adusumilli S, Hussain HK, Caoili EM et-al. MRI of sonographically indeterminate adnexal masses. AJR Am J Roentgenol. 2006;187 (3): 732-40. doi:10.2214/AJR.05.0905 - Pubmed citation
- 4. Friedman AC, Pyatt RS, Hartman DS et-al. CT of benign cystic teratomas. AJR Am J Roentgenol. 1982;138 (4): 659-65. AJR Am J Roentgenol (abstract) - Pubmed citation
- 5. Patel MD, Feldstein VA, Lipson SD et-al. Cystic teratomas of the ovary: diagnostic value of sonography. AJR Am J Roentgenol. 1998;171 (4): 1061-5. AJR Am J Roentgenol (abstract) - Pubmed citation
- 6. Buy JN, Ghossain MA, Moss AA et-al. Cystic teratoma of the ovary: CT detection. Radiology. 1989;171 (3): 697-701. Radiology (abstract) - Pubmed citation
- 7. Park SB, Kim JK, Kim KR et-al. Imaging findings of complications and unusual manifestations of ovarian teratomas. Radiographics. 28 (4): 969-83. doi:10.1148/rg.284075069 - Pubmed citation
Synonyms & Alternative Spellings
|Synonyms or Alternative Spelling||Include in Listings?|
|Benign cystic teratoma of ovary||✓|
|Mature ovarian teratoma||✗|
|Mature cystic teratoma of ovary||✓|
|Ovarian mature cystic teratoma||✗|
|Dermoid cyst of the ovary||✗|
|Ovarian dermoid cyst||✓|