Epignathus

Epignathus is a term given to a very rare form of teratoid tumour that arises from the oropharyngeal region.

Epidemiology

There may be a slight female predilection ^ref. The estimated incidence is ~ 1 in 35,000 to 200,000 births.

Clinical presentation

The tumour classically presents in utero or in the neonatal period. In extreme rare occasions, it may present in young children ⁹.

Pathology

It is often classified under the broader umbrella of cervical teratomas. The tumours are not often consistent in origin, number, and differentiation of tissues. They usually have components from all three germ layers and can contain fat, cartilage and bone. 

Location

The tumour typically arises from the palato-pharyngeal region around the basisphenoid (Rathke's pouch) and with progressive growth fills the buccal cavity and finally protrudes out of the mouth. 

Associations

• polyhydramnios: when there is associated swallowing impairment
• mid line facial dafects
  • cleft lip and/or palate

Markers

• raised maternal serum alpha feto protein (MSAFP)

Radiographic features

Antenatal ultrasound

Usually seen as a complex mass protruding from the fetal oral cavity (often with mixed echogenecity ¹¹). Accompanying polyhydramnios may be present when there is swallowing impairment.

MRI

Useful for better delineation of anatomy.

Treatment and prognosis

The prognosis is generally poor (often as a result of its location) and part of the high mortality rate is caused by severe airway obstruction in the neonatal period. The tumour may also demonstrate rapid growth. An EXIT procedure can be offered in selected cases ⁶.

Complications

• development of fetal hydrops: often due to tumour shunting/using a lot of blood flow 
• the tumour can spread superiorly destroying the skull base and brain tissue ¹²
  • this in turn can give a range complications such as fetal hydrocephalus
• neonatal death usually occurs due from airway obstruction and consequent asphyxia after birth

Differential diagnosis

In general consider other tumours from the oropharyngeal region:

• oropharyngeal rhabdomyosarcoma
• epulis/congenital oral granular cell myoblastoma ¹³

For small lesions on a sagittal ultrasound scan also consider:

• macroglossia
• prominent philtrum/premaxillary tissue  from a midline facial defect (can also be an association)

See also

• congenital cervical teratoma