Figure 4: Cut section of the teratoma.
On microscopic examination of the cervicofacial tumor, an organoid growth pattern was observed. Both mature and immature teratomatous tissues were identified. The immature teratoma was represented predominately by immature neuroepithelium. The amount of neuroepithelium present was characteristic of a histologically grade 3 (Norris classification) immature teratoma1. There was no evidence of metastatic disease.
Representative sections of the visceral organs showed development that was appropriate for the estimated gestational age. The visceral organs were uninvolved by the tumor, and no other anomalies were noted. Examination of the placenta revealed a late second trimester placenta with focal hydropic degeneration of the chorionic villi.
Discussion
Definition
Teratomas are complex neoplasms consisting of multiple various tissue types and occurring at sites foreign to their natural anatomic origin. Typically, teratomas contain derivatives from all three germinal layers. They generally appear by ultrasound to contain cystic and solid components. Teratomas may be encountered at numerous sites. Cervical teratomas, in particular, are frequently large and mobile, usually emanating from the lateral aspect of the neck. Cervical teratomas need be considered in the differential diagnosis of any fetal mass in the head and neck region.
Prevalence
Perinatal neoplasms account for just 2-3% of all childhood tumors, with teratomas the most common variety2. The incidence of congenital teratoma is reported as 1:20,000 to 1:40,000 live births3. Location as noted above is variable. They are most frequently found in the sacrococcygeal area, although other sites include cranial, orbital, nasopharyngeal, thyroidal, cervical, mediastinal, retroperitoneal and gonadal4. Cervical teratomas are quite rare, accounting for 5.5% of all fetal teratomas3,5. The first known case was reported in 18546.
Etiology and pathogenesis
The etiology and pathogenesis of teratomas are presently unclear, although numerous theories have been proposed. The diverse cellular origins of teratomas have sparked debate regarding the histogenesis of these tumors. Theoretical sources of teratomas include 1) displaced primordial germ cells, 2) embryonic cells, 3) extraembryonic cells, 4) inclusion of conjoined or maldeveloped twins, 5) totipotent stem cells or 6) pluripotent cell types native to the site of origin of the teratoma7. One hypothesis purports that teratomas located in the anterior portion of the neck originate from embryonic cells in the primitive thyroid anlage, while another theory states that these tumors may result from incomplete twinning in which blastula stage cells separate and form a partial embryo. The latter is supported by evidence of teratomas that arise at sites where conjoined twins occur6. Despite numerous and varied theories, no single one adequately captures the etiology and/or pathogenesis of cervical teratomas.
Associated anomalies
Other anomalies should be ruled out whenever the diagnosis of a fetal teratoma is considered. Anomalies associated with sacrococcygeal teratomas are better known than those associated with the more rare cervical teratomas. Musculoskeletal, renal and neural abnormalities have been discovered in approximately 18% of teratomas in the sacrococcygeal region7. Abnormalities associated with cervical teratomas have been reported and include cystic fibrosis, hypoplastic left ventricle with pulmonary hypoplasia, chondrodystrophia fetalis and imperforate anus8.
Complications
Multiple complications may result from cervical teratomas. Hemorrhage into the cervical mass, either prenatally or intrapartum, may cause fetal decompensation. Early neonatal death most often results from lethal respiratory distress secondary to tracheal compression from the mass. Non-immune fetal hydrops can also result, which may lead to fetal demise. The mechanism is believed to be a tumor-mediated arteriovenous shunt, leading to high output failure9. Fetal tumors constitute 5-7% of cases of fetal hydrops10.
Polyhydramnios is another possible complication in cases of fetal cervical teratomas, seen in 30% of cases. Anatomically, these masses may interfere with swallowing and therefore lead to an accumulation of amniotic fluid11. Both the polyhydramnios and the sheer tumor size may cause increased uterine distention, resulting in preterm labor. Over-distended uteri from polyhydramnios have been known to cause maternal ureteral obstruction, resulting in oliguria, anuria or even acute obstructive renal failure12,13,14.
Differential diagnosis
A differential diagnosis of cervical masses should include meningocele, cystic hygroma, lymphangioma, hemangioma, fetal goiter, branchial cleft cyst, macerated twin fetus and cervical teratoma. Detailed and careful ultrasonographic evaluation, aided by color flow Doppler, should differentiate the above on most occasions. A well defined, partially cystic, partially solid mass at the anterolateral portions of the fetal neck with hyperextension of the neck is characteristic of a cervical teratoma.
Prognosis
The prognosis of fetuses with cervical teratomas is quite poor. Approximately 50% of these fetuses die in utero, while those infants born alive have a 50% mortality rate from respiratory complications immediately postpartum11. The prognosis is related to the size of the mass and surgical operability. Other prognostic factors include gestational age of the fetus at the time of delivery, presence or absence of associated fetal malformations, presence or absence of fetal hydrops and the availability of a resuscitation team to secure a neonatal airway following delivery10.
Recurrence risk
There is no increased recurrence risk of fetal cervical teratomas, as they are not believed to be inherited in a Mendelian or polygenic fashion3.
Management
The prenatal diagnosis of a cervical teratoma allows for a management approach tailored to meet its anticipated complications15. Although prenatal ultrasonic diagnosis has not yet affected mortality from cervical teratomas, it is hoped that with further experience and a management team approach, mortality can be reduced5. In the event of a prenatally diagnosed cervical teratoma, a careful ultrasonic evaluation should be undertaken to rule out other anomalies4. Serial ultrasound examinations should be performed to document the growth of the teratoma as well as the development of any complications, such as fetal hydrops.
Many of these infants die secondary to prematurity. The degree of lung function is a limiting factor in the extrauterine survival of these neonates2. Tocolysis along with other modalities (e.g. therapeutic amniocentesis for polyhydramnios) to delay delivery in a fetus with known or suspected pulmonary immaturity should be employed when necessary7. In the future, fetal surgery may provide a means to resect the lesion and hence prolong gestation10. Cesarean section, especially for large tumors, is indicated to avoid birth dystocia and/or teratoma avulsion3.
The most urgent complication in a neonate with a cervical teratoma is a compromised airway. The establishment of a secure airway is therefore paramount. The effort to establish an airway can be optimized by maintaining an intact maternal-fetal circulation until that airway is guaranteed5. Endotracheal intubation or emergency tracheotomy must be prepared for. Further immediate surgical intervention (i.e. tumor resection) should be anticipated in cases of large cervical teratomas.
The team approach is of utmost importance in providing an organized and coordinated care plan. An obstetrician and/or perinatologist, neonatologist, pediatric surgeon and if necessary, anesthesiologist and otolaryngologist should all be available in the delivery suite for the birth, resuscitation and possible surgical intervention of the neonate5,7. At present, surgical removal offers the best potential for survival and cure.
References
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Published in The Fetus in 1994. posted 6/1999