- 1 in 50,000 births.
- 5% of all fetal teratomas.
- Vascular solid mass with cystic components, located anterior or anterolateral to the fetal neck. The tumor grows rapidly (especially >26 weeks' gestation due to materal estrogens) and can extend inwards producing hyperextension of the neck and polyhydramnios.
- Calcifications are found in about 50% of cases.
- The incidence of chromosomal defects and genetic syndromes is not increased.
- Large tumours may result in fetal anemia and thrombocytopenia (due to sequestration of red blood cells and platelets by the tumor), fetal heart failure, hydrops and placentomegaly (due to a hyperdynamic circulation as a result of arteriovenous shunting), polyhydramnios (due to direct transudation into the amniotic fluid and due to fetal polyuria, secondary to the hyperdynamic circulation) and maternal mirror syndrome (generalized fluid overload and preeclampsia).
- Detailed ultrasound examination, including echocardiography for assessment of cardiac function and measurement of fetal middle cerebral artery peak systolic velocity (MCA PSV) for diagnosis of fetal anemia.
- Fetal MRI at 32 weeks to assess the relation to adjacent structures.
Follow-up scans every 2 to 3 weeks to monitor growth of the tumor, heart function, MCA PSV and amniotic fluid volume.
Ultrasound guided laser coagulation of vessels within the tumor, fetal blood transfusions and amniodrainage may become necessary.
- Place: hospital with neonatal intensive care and pediatric surgery.
- Time: 38 weeks. Earlier if there is evidence of poor growth, fetal hypoxia or hydrops.
- Delivery: cesarean section with EXIT procedure.
- Fetal or neonatal death (due to airway obstruction) in about 80% of cases.
- Survival after surgery is >80% however, extensive neck dissection and multiple additional procedures are necessary to achieve complete resection of the tumor with acceptable functional and cosmetic results.
- No increased risk of recurrence.