Cervical teratoma is a rare tumor. Approximately 300 congenital cases have been described (Riedlinger et al., 2005; Oka et al., 2007). Since the first prenatal diagnosis of fetal cervical teratoma in 1978, there have been only a few dozen published reports of cervical masses detected in utero (Schoenfeld et al., 1978; Patel et al., 1982; Suita et al., 1982; Kagan, 1983; Thurkow et al., 1983; Trecet et al., 1984; Pearl et al., 1986; Cunningham et al., 1987; Hitchcock et al., 1987; Holinger and Birnholz, 1987; Roodhooft et al., 1987; Jordan and Gauderer, 1988; Kelly et al., 1990; Zerella and Finberg, 1990; Baumann and Nerlich, 1993; Liechty et al., 1997; O’Callaghan et al., 1997).

As in other teratomas, cervical teratomas are composed of tissues foreign to their normal anatomic sites. All three germ layers are represented within the tumor. Neural tissue is the most common histologic component, with cartilage and respiratory epithelium also observed (Schoenfeld et al., 1982). Thyroid tissue occurs in 30% to 40% but it is uncertain whether this represents actual involvement of the gland or ectopic thyroid tissue (Jordan and Gauderer, 1988). Theories regarding the origin of cervical teratoma include derivation from totipotential germ cells or abnormal development following cleavage of monozygous twins with fetus in feta (Ashley, 1973; Hitchcock et al., 1987).

Cervical teratomas are rare with an incidence ranging from 1 in 20,000 to 1 in 40,000 livebirths (Azizkhan et al., 1995).

Cervical teratomas account for 3% to 6% of teratomas (Azizkhan et al., 1995, Jordan and Gauderer, 1988). There is no apparent relationship to maternal age or parity (Hitchcock et al., 1987). Unlike other teratomas, males and females are equally affected (Batsakis et al., 1964; Tapper and Lack, 1983) and there is no racial predilection (Suita et al., 1982).

On ultrasound examination, cervical teratomas are typically asymmetric, unilateral, mobile, and well demarcated (Figures 110-1 to 110-3). Most are multiloculated, irregular masses with solid and cystic components (Figure 110-1). As many as 50% have calcifications present (Gundry et al., 1983; Kelly et al., 1990). Calcifications may be difficult to appreciate on ultrasound examination and are more easily seen on plain radiographs (Goodwin and Gay, 1965; Hajdu et al., 1966; Suita et al., 1982). Calcifications, when present in a partially cystic and solid neck mass, are virtually diagnostic of cervical teratoma (Gundry et al., 1983).

Cervical teratomas are usually large and bulky, typically measuring 5 to 12 cm in diameter (Silberman and Mendelson, 1960; Batsakis et al., 1964; Liechty et al., 1997; Liechty and Crombleholme, 1999; Crombleholme and Albanese, 2001). Tumor masses greater than the size of the fetal head have also been reported (Figure 110-4) (Batsakis et al., 1964; Owor and Master, 1974; Jordan and Gauderer, 1988). These tumors usually extend to the mastoid process and body of the mandible, superiorly displacing the ear. Inferiorly they can extend to the clavicle and suprasternal notch or extend into the mediastinum. Posteriorly, they can extend to the anterior border of the trapezius. Involvement of the oral floor, protrusion into the oral cavity (epignathus), and extension into the superior mediastinum have also been noted in cervical teratomas (Jordan and Gauderer, 1988).

Polyhydramnios will complicate 20% to 40% of the prenatally diagnosed cases and is more commonly observed in large tumors (Bale, 1949; Lloyd and Clatworthy, 1958; Hajdu et al., 1966; Trecet et al., 1984). Polyhydramnios is thought to be due to esophageal obstruction, as has been demonstrated by contrast amniography (Rosenfeld et al., 1979; Mochizuki et al., 1986). An emptystomach may be the first sonographic clue to esophageal obstruction from cervical teratoma (Rosenfeld et al., 1979; Suita et al., 1982). Other anomalies have been reported in association with cervical teratomas, including one case each of chondrodystrophia fetalis and imperforate anus (McGoon, 1952). Hypoplastic left ventricle and trisomy 13 have also been reported in association with cervical teratoma (Gundry et al., 1983; Dische and Gardner, 1987), as has agenesis of the corpus callosum (Goldstein and Drugan, 2005). Mandibular hypoplasia may also be seen as a direct result of mass effect on the developing mandible (Liechty et al., 1997).

The fetus with a large cervical teratoma often has a marked extension of the neck due to mass effect. The cervical teratomas are deeper than the strap muscles of the neck, thus causing severe compression of the larynx, trachea, and esophagus. As noted above, esophageal compression results in polyhydramnios, and compression of the larynx and trachea can result in not only deviation and distortion of the airway, but also marked laryngotracheomalacia. The hyper-extension of the fetal neck may also result in profound pulmonary hypoplasia. The hyperextended neck pulls the fetal trachea cephalad, and in severe cases the carina can be found above the level of the thoracic inlet. This pulls the lungs into the cupola of the thoracic cavities, preventing normal lung growth. Several cases of death due to profound pulmonary hypoplasia have been reported despite successful EXIT (ex utero intrapartum treatment) procedures to secure the airway (Liechty and Crombleholme, 1999; Crombleholme and Albanese, 2001).

Cystic hygroma is the most likely entity to be mistaken for cervical teratoma in cases detected prenatally (see Chapter 32). The similarities in size, sonographic findings, clinical characteristics, location, and gestational age at presentation make this distinction difficult (Batsakis et al., 1964). Cystic hygromas are typically multiloculated cystic masses with poorly defined borders that infiltrate the normal structures of the neck. This contrasts with the usually well-defined borders of cervical teratomas. Furthermore, cystic hygromas tend to be smaller than cervical teratomas, are unilateral, and more frequently involve the posterior triangle (Pearl et al., 1986).

Many other entities may resemble a cervical teratoma on sonographic imaging (Table 110-1). Amniotic fluid α-fetoprotein (AFP) has been suggested as an aid in the differential diagnosis of a cervical mass. However, maternal and fetal AFP levels may be either elevated or normal in cervical teratomas. Because fewer than 30% of cervical teratom as have an elevated AFP (Schoenfeld et al., 1982; Trecet et al., 1984), this assay is not particularly helpful in the differential diagnosis of fetal cervical masses. An elevated serum AFP level in the newborn, however, may be helpful in following the patient for signs of teratoma recurrence after successful resection. The preoperative values may be difficult to interpret, as AFP levels are high in normal newborns

Vascular malformations are another important condi-tion in the differential diagnosis. These lesions may be both cystic and solid, like cervical teratomas, but do not have calcifications. These lesions are often quite vascular and color flow Doppler images often reveal the extensive vascularity of these lesions. Flow through either cervical teratomas or vascular malformations can result in high-output failure, and echocardiographic assessment of combined ventricular output is indicated in all cases.

Fetal MRI has proven particularly useful in distinguishing the complex, septic, and solid teratoma from lymphangioma(see Figure 110-2) (Liechty et al., 1997; Hubbard et al., 1998). An MRI allows a larger field of view than an ultrasound and may show better tissue contrast (Figure 110-4). The T₁ and T₂-weighted imaging may allow fat to be identified within the lesion, which is more consistent with a diagnosis of cervical teratoma than cystic hygroma or vascular malformation (Hubbard et al., 1998).