**6.2. Epignathus**

**Definition:** A teratoma that arises from the oral cavity or pharynx.

**Incidence:** 2% of all pediatric teratomas occur in the nasopharyngeal area (including oral, tonsillar, and basicranial areas). The majority of cases occur in newborn [43, 44].

**Pathology:** Tumors arise mainly from the sphenoid bone; they rarely arise from other areas (the hard and soft palate, the pharynx, the tongue, and jaw). These tumors grow into the oral or nasal cavity or intracranially. Obstruction of the mouth is responsible for polyhydramnios. Most tumors are benign, consisting histologically of tissues derived from any of the three germinal layers. They can fill the mouth and airways and lead to acute asphyxia immediately after birth [44].

**Ultrasound diagnosis:** Solid tumor arising from the sphenoid bone, hard and soft palate, the pharynx, the tongue, and the jaw. The tumor may grow into the oral or nasal cavity or intracranially. Calcifications and cystic components may also be noticed. The differential diagnosis will include neck teratomas, encephaloceles, conjoined twins, and other tumors of the facial structures. Polyhydramnios (due to pharyngeal compression) is usually present.

**Associated abnormalities:** This is a sporadic condition, with no increased incidence of chromosomal defects or genetic syndromes; only 6% of these tumors have associated anomalies, and the facial ones being attributed to the mechanical effects of the tumor on developing structures [45].

**Investigations:** Scans every 4 weeks to monitor the growth of the tumor and assess the amniotic fluid. If polyhydramnios develops, amniodrainage may be balanced. Fetal MRI is recommended at 32 weeks to assess the spatial relation of the tumor to adjacent structures.

**Prognosis:** It depends on the size of the lesion and the involvement of vital structures. The lesions are usually very large, and the polyhydramnios associates a poor prognosis. The major cause of neonatal death is asphyxia due to airway obstruction. Surgical resection is possible at times. There are no reported cases of malignancies [46–49].

Fetuses with large tumors are best delivered by cesarean section, and an expert pediatric team must be available to intubate of the infant.
