• Teratomas are germ cell tumours that arise
from ectopic pluripotent stem cells that fail to
migrate from yolk sac endoderm to the
urogenital ridge during embryogenesis.
• By definition, they contain elements from all
three embryological layers: endoderm,
mesoderm and ectoderm although frequently.
• Teratomas range from benign, mature, welldifferentiated cystic lesions to immature,
poorly differentiated lesions with solid
components and malignant transformation.
• As a result they can contain a large variety of
tissue types including. On occasion, mature
teratomas contain elements that undergo
malignant transformation (most commonly
– cystic spaces due to mucous production or other
– soft-tissue from any part of the body
– calcification including teeth
• ovary : also known as ovarian dermoid cyst
• testis : testicular teratoma
• mediastinum : mediastinal teratoma
– account for 27% of all teratomas in adults
– account for 4-13% of all teratomas in children
• intracranial : intracranial teratoma
• sacrococcygeal region : sacrococcygeal
• Ovarian teratomas is the most common group
of ovarian germ cell tumours
• They can be divided into 3 main sub types
– mature ovarian teratoma
– immature ovarian teratoma
– specaliased teratoma
• struma ovarii tumour
Mature (cystic) ovarian teratoma
• Ovarian dermoid cyst and mature cystic teratoma
are terms often used interchangeably to refer to
the most common ovarian neoplasm.
• The two have a fundamental histological
– dermoids are composed only of dermal and epidermal
– teratomas have mesodermal and endodermal
• Mature cystic teratomas account for 10-20%
of all ovarian neoplasms.
• They tend to be identified in young women,
typically around the age of 30 years and are
also the most common ovarian neoplasm in
patients younger than 20 years.
• Mature cystic teratomas are encapsulated
tumors with mature tissue or organ
• They are composed of well-differentiated
derivations from at least two of the three
germ cell layers.
• Real organoid structures (teeth, fragments of
bone) may be present in ~ 30% of cases.
• Plain film
– May show calcific and tooth components with the
• Pelvic ultrasound
– 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.
– CT has high sensitivity in the diagnosis of cystic teratomas.
– Typically CT images demonstrate fat, 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
– When ruptured, the characteristic hypo-attenuating fatty
fluid can be found as ante-dependent pockets, typically
below the right hemidiaphragm, a pathognomonic finding.
– The escaped cyst content also leads to a chemical
peritonitis and the mesentery may be stranded and the
peritoneum thickened, which may mimic peritoneal
• Pelvic MRI
– 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.
• ovarian torsion : ~ 3-16% of ovarian teratomas,
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).
• suprimposed infection : 1%
• autoimmune haemolytic anaemia : < 1%.
• hemorrhagic 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
10 M/O, Male
• Intracranial teratoma are uncommon
intracranial neoplasms, which can have a wide
range of appearances.
• They can be divided into two broad
categories, intra and extra-axial.
• Another method of classifying an intracranial
teratoma is as mature, immature and mature
with with malignant transformation.
• Clinical presentation varies according to whether they are intra- or
– Intra-axial teratoma, typically present either antenatally or in the
– They are large tumors that increase head circumference and therefore
often present with difficulty in child birth. They tend to more
commonly occur supratentorially.
– Extra axial teratoma usually present in childhood or early adulthood
and are typically smaller.
– They most commonly arise in the pineal or suprasellar regions, and
present due to mass effect: obstructive hydrocephalus due to
impingement on the mid brain, Parinaud's syndrome, optic chiasm
• Teratoma are considered intracranial germ cell
tumors, and are comprised of cells originating
from at least two and usually all three
embryonic layers : ectoderm, mesoderm and
• The histological sub type may not necessarily
determine the biological behavior.
• Intracranial teratoma are often seen as large
lesions at presentation.
• Given their extremely variable histological
components, imaging also tends to be
heterogenous, with tumors typically
demonstrating a mixture of tissue densities
and signal intensity. Fat, if present is helpful in
narrowing the differential.
– The majority of intracranial teratomas
demonstrate at least some fat and some
calcification, which is usually solid / "clump like".
– They usually have cystic and solid components,
contributing to an irregular outline. Solid
components demonstrate variable enhancement.
• hyperintense components due to fat and proteinaceous
/ lipid rich fluid
• intermediate components of soft tissue
• hypointense components due to calcification and blood
– T1 C+ (Gd) : solid soft tissue components show
– T2 : again mixed signal from differing components
• A meaningful differential depends to a degree on
– atypical rhabdoid / teratoid tumour (ATRT) : older age
– choroid plexus carcinoma
intracranial lipoma : fatty components only
intracranial dermoid : more mature tissue
craniopharyngioma : particularly for suprasellar lesions
other pineal region tumors
Hypodensity lesion (HU value around -100) indicates fat contained.
Tumor spread to CP angle cistern, temperal lobe region, and suprasellar cistern,
• The case was suspected epidermal cyst at first
due to almost lipid content.
• However, the pathology report showed a