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Sacrococcygeal Teratoma
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Types
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A teratoma, in general terms, is a tumor containing at least two of the three main
layers of the fetus. In teratomas in the newborn/fetus, it is common to find a tumor
composed mainly of nervous system tissue (almost always), fat, muscles, cartilage
and bones, whereas other components are less frequent.
- In the adult, most teratomas are situated in the ovaries.
- In the fetus, a teratoma in the sacrococcygeal area is more common (this is the
lowest part of the back).
The differentiation of the various types is based on the degree of outward spread
of the tumor and its spread in the pelvis:
- Type 1: 45% - the tumor is mainly outside the body with minimal pelvic involvement.
- Type 2: 44% - the tumor is outside the body but there is also a significant intrapelvic
component.
- Type 3: 8% - the significant component of the tumor is mainly within the true pelvis
in the abdomen, but some is also externally visible.
- Type 4: 3% - the tumor is internal only without an external component. 2% of cases
of sacrococcygeal teratomas grow into the spinal column.
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Clinical signs
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The frequency is 1 in every 40,000 live births and the condition is four times more
common in females.
There are reports that malignant tumors are more common in males.
In most cases, the tumors are relatively large (8-10 cm) and encased in skin.
Within the tumor itself, there are regions of solid tissue that can contain many
blood vessels, and cystic regions that are full of fluid.
It is important to differentiate the teratoma from other tumors or processes that
may be situated in the same region of the body - these, however, are less common.
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Additional complications
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- In cases detected at or immediately after birth: if the tumor is not excised, it
may undergo malignant transformation - 90% of teratomas are benign, and 10% are
malignant of the adenocarcinoma type. In approximately 7% of cases of teratomas
detected at birth, there is obstruction of the intestines or disorder of the functioning
of the urinary bladder - these problems usually resolve when the tumor is excised.
- In cases detected later, after the age of two months, the complications are more
severe - 90% of cases are malignant (adenocarcinoma). In approximately 80% of cases
of teratomas, there is intestinal obstruction or urinary bladder dysfunction.
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What are the risks to the fetus if the tumor is detected in utero?
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One study described in the literature reported that out of 134 fetuses with sacrococcygeal
teratoma, intrauterine death occurred in 41 (35%). This occurred mainly in the cases
where the tumor was very large, with a proliferation of blood vessels. In these
cases the placenta is large and there is a risk of heart failure, edema, and later
intrauterine death.
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What are the consequences when the tumor is discovered after birth?
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The results depend on how premature the birth is, since sacrococcygeal teratoma
may lead to premature birth due to
polyhydramnios,s the method of delivery (cesarean section is preferable,
and advisable in any case of a tumor of over 10 cm diameter); the degree of blood
loss due to serious hemorrhages, which occur mainly in large tumors where there
is proliferation of blood vessels; and the promptness of diagnosis and surgical
intervention. If the teratomas are not discovered early, 50% - 60% of them undergo
malignant transformation between the ages of 4 months and 5 years. Usually, therefore,
when the tumor is not very large, it does not contain many blood vessels, there
is no malignancy in the tumor, an early diagnosis is made, and immediate intervention
is undertaken, then the prognosis is good.
A number of cases of surgical intervention in fetuses in utero have been reported
in the literature. The goal was to excise the tumor together with the coccyx bone,
thus preventing heart failure in cases where the tumor was large. The outcomes were
no better than cases that did not undergo this trial operation.
There are a number of hypotheses concerning the formation of this tumor:
- A tumor originating from a multipotential fetal cell, which can develop into a diverse
number of tissues.
- Incomplete separation and lack of development of one of two twins during fetal development.
- A tumor arising from a release of mitogens (cell division stimulants), leading to
increased cell division in growth areas.
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Inheritance pattern
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In most cases, occurrence is sporadic, i.e. there is a single case in the family
without recurrence. Twenty-six cases of familial transmission have been described
with an autosomal dominant inheritance pattern. The familial cases were marked by
equal male to female ratios, all had a tumor at the front of the coccyx bone, were
associated with congenital anal atresia, and usually the tumors were benign.
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Penetrance
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Not known
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Associated features that can be demonstrated in tests performed during pregnancy
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The ultrasound findings are usually just the tumor itself. In the tumor, regions
of solid tissue can be discerned, containing cysts with an irregular shape and arrangement.
The cysts can be situated in the center or the periphery of the tumor. The solid
regions may have variable echogenesis. Sometimes the structure can be cystic only
or solid only. Usually, teratomas are rich with blood vessels, and these are well
demonstrated using the color Doppler technique, which specifically demonstrates
blood flow.
The possibility of heart failure must be considered. In these cases, a large liver,
a large, fleshy placenta and diffuse edema can be seen. Sometimes in these cases
only polyhydramnios is visible.
Postnatal reports describe associated defects in 15% of cases, despite the fact
that these were not detected by regular ultrasound examination. There is no increase
in the frequency of chromosome disorders in these cases.
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What is the risk of recurrence in a subsequent pregnancy?
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Healthy parents who have had an affected child are not at a significantly high risk
for having another affected child. A parent who suffered from this condition and
was operated on and recovered has a slightly increased risk for having an affected
child - the exact risk is determined within
genetic counseling.
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Molecular genetic information
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The gene for the disease
Not known
Location
Not known
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Genetic testing
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Diagnostic testing
Ultrasound examination
Carrier testing
Not available
Fetal testing
Ultrasound examination
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