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teratomas in the head and neck account for 29% of all teratomas at birth and teratomas in the oropharynx are extremely rare . here , we present a case of oropharyngeal teratoma that was diagnosed antenatally .
a 25-year - old female ( gravida 2 para 1 ) was seen by a radiologist for evaluation of polyhydraminos .
ultrasound evaluation of the fetus revealed no significant abnormalities [ figure 1 ] . fetal spine and facial structure were normal .
amniotic fluid volume was greater than normal , amniotic fluid index ( afi ) measured 45 cm .
some problem in fetal swallowing due to small stomach and polyhydraminos was suspected . a fetal magnetic resonance imaging ( mri )
was done to evaluate cause of acute polyhydramnios and relatively small size of the stomach .
ultrasound image of fetal face in sagittal projection shows shadow from the hard palate ( arrow ) obscuring the pharyngeal mass . fetal mri done on 1.5 t philips achieva magnet with t2w turbo spin echo sequences and balanced turbo field echo sequences .
sagittal [ figure 2 ] and axial [ figure 3 ] images show well - defined mixed intensity lesion with cystic component measuring about 4.5  3.5 cm in the oropharyngeal region
. no obvious sign of invasion of hard palate or nasopharynx was noted [ figure 2 ] .
sagittal image of fetal mri at 34 weeks gestation shows well - defined mixed intensity lesion with cystic component measuring about 4.5  3.5 cm in oropharyngeal region ( arrow ) .
axial image of fetal mri at 34 weeks of gestation shows well - defined mixed intensity lesion with cystic component measuring about 4.5  3.5 cm in oropharyngeal region ( arrow ) . because of
surgery for tumor removal was planned and done on the fourth day after birth . at surgery ,
well - defined lobulated tumor measuring about 4.5  3.4 cm arising from palate was resected [ figure 4 ] and sent for histopathology examination .
after 4 weeks , the baby 's serum alfa - feto - proteins were found to be elevated to 600 ng / ml . parents were advised to consult a medical oncologist , who advised follow - up after 6 months .
after 6 months , positron emission tomography - computed tomography [ figure 7 ] was done to rule any recurrence .
serum alpha - feto - protein was repeated and found to be 180 ng / ml . medical oncologist advised chemotherapy and radiation but the parents did not agree to this treatment .
presently , the boy is 27 months old and doing well without any clinical symptoms .
histopathology examination of the surgically removed mass shows mass composed of mature and immature elements of teratoma .
easiest immature element to identify is neuroepithelium with columnar cells forming rossettes and tubules ( arrow ) .
surgically removed mass stained with hematoxylin and eosin at 45 shows mature cartilaginous tissue ( arrow ) .
pet ct image of the child , 6-months posttreatment shows metabolic activity in the tongue and adenoids are physiological . soft palate ( arrow ) , where the original tumor was resected is normal indicating no recurrence of tumor .
teratoma is a true neoplasia containing cells of all the three germ lines and represent 25 - 30% of all neonatal tumors .
teratomas can occur in any part of the body but are most common in the sacro coccygeal region .
teratomas of head and neck region are extremely rare and are most common in the cervical region followed by the oropharyngeal region .
oropharyngeal teratomas appear as heterogenous masses with solid and cystic components and are believed to be result of migration and entrapment of mesoderm and endoderm with ectoderm during embryogenesis .
sometimes the mass can not be appreciated in usg due to the presence of shadows . in our case
fetal mri was helpful in diagnosing and revealing the extent of oropharyngeal involvement , defining tracheal anatomy , and excluding intracranial involvement .
mri is more useful to delineate soft tissues and can give a near accurate assessment of oropharyngeal extension .
ct was not done antenatally in our case as the tumor was well - defined and limited to oropharynx and also to minimize radiation exposure to our patient .
pet ct was done on the baby at 6 months of age to look for recurrence or metastasis .
oropharyngeal teratoma can encroach airway and cause respiratory distress , progressive dysphagia , and aspiration pneumonia due to impaired swallowing mechanism .
antenatal diagnoses of oropharyngeal teratoma is essential as it can radically change the treatment and allows the medical team to plan for ex utero intrapartum treatment ( exit ) or management during early neonatal period with surgery .
exit is a technique designed to allow partial fetal delivery via cesarean section while a safe fetal airway is established .
upon delivery of the fetal head , neck , and one or both upper limbs , a stepwise , sequential attempt to secure the neonates airway is performed via laryngoscopy , bronchoscopy , tracheostomy , or even resection of the obstructing mass .
the placenta remains in utero to maintain feto - placental circulation and subsequently the continuance of fetal oxygenation .
once the newborn 's airway is secured , the umbilical cord is clamped and delivery of the infant completed .
this technique was first described in 1990 by zerella and finberg to improve the survival of fetuses with head and neck teratomas and also by levine et al .
the use of exit has also proven to be effective for the management of fetal airway obstruction due to a variety of other causes including congenital high airway obstruction syndrome ( chaos ) , intrathoracic masses , and congenital diaphragmatic hernias .
mri proved superior to ultrasound in diagnosing and delineating exact tumor location , size , extension , and was crucial in determining timing and mode of delivery .
oro - pharyngeal teratoma because of its potential to cause airway obstruction , though rare , should be considered while investigating polyhydramnios .
early antenatal diagnosis allows the medical team to plan mode of delivery , management through exit procedure or surgery during the early neonatal period and ultimately leads to better outcome .
oropharyngeal teratomas are extremely rare congenital tumors and have an incidence rate of one in 35,000 - 200,000 newborn babies / neonates . 
 oropharyngeal teratomas may cause life threatening airway obstruction to a newborn . 
 early diagnosis with ultrasound and magnetic resonance imaging ( mri ) is essential to plan management . here , we present a rare case of oropharyngeal true teratoma diagnosed with mri antenatally in a fetus at 34 weeks of gestation in a 25-year - old female who was being evaluated for polyhydraminos . 
 we found mri to be more helpful for antenatal diagnosis , counseling , and management than ultrasonography and computed tomography ( ct ) .