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Sacrococcygeal Teratoma


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.

Clinical signs

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.

Additional complications

  • 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.

What are the risks to the fetus if the tumor is detected in utero?

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.

What are the consequences when the tumor is discovered after birth?

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:
  1. A tumor originating from a multipotential fetal cell, which can develop into a diverse number of tissues.

  2. Incomplete separation and lack of development of one of two twins during fetal development.

  3. A tumor arising from a release of mitogens (cell division stimulants), leading to increased cell division in growth areas.

Inheritance pattern

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.


Not known

Associated features that can be demonstrated in tests performed during pregnancy

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.

What is the risk of recurrence in a subsequent pregnancy?

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.

Molecular genetic information

The gene for the disease

Not known


Not known

Genetic testing

Diagnostic testing

Ultrasound examination

Carrier testing

Not available

Fetal testing

Ultrasound examination
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