venerdì 8 febbraio 2008

Nasopharyngeal teratoma


Figure 1 and Figure 2: Centered within the nasopharynx, there is a large heterogeneous, soft tissue mass with associated calcifications. There is no associated bony destruction or intra-cranial extension.
Figure 3, Figure 4, and Figure 5: MRI of the brain reveals a large complex mass with sold and fatty areas centered within the nasopharynx. Areas of low signal within the mass correspond to calcifications visualized on CT images. There in no intracranial extension or visualized intracranial abnormality. A normal pituitary gland and sella turcica can be appreciated on the sagittal image (Figure 3).

Diagnosis: Nasopharyngeal teratoma

Neonatal teratomas are very rare congenital tumors which are formed from cells derived from all three embryonic germ cell layers. The incidence of neonatal teratomas is between 1:20,000 and 1:80,000 live births. Most occur in the sacrococcygeal region and only 5% are found in the head and neck region, specifically the cervical region followed by the nasopharynx. They can be associated with a cleft palate, intracranial abnormalities including hemicrania and anencephaly, other head and neck anomalies, diaphragmatic hernia and renal and vertebral anomalies.

Nasopharyngeal teratomas most commonly present with difficulties in swallowing and obstructive respiratory distress. The size and location serve as the major causes of morbidity and mortality. Rapid airway stabilization, including endotracheal intubation, cricothyrotomy or tracheotomy, is crucial in the management of these patients. After securing the airway, imaging is very useful to help differentiate this tumor from other masses. Ultimately surgical excision is the mode of treatment. These tumors are often encapsulated or pseudoencapsulated which yields excellent surgical prognosis.

The differential diagnosis for neonatal nasopharyngeal lesions is extensive and includes: teratoma, dermoid, craniopharyngioma, encephalocele, cystic hygroma, rhabdomyoscarcoma, hemangioma, lipoma, chordoma, neurofibroma, Rathke’s pouch and sarcoma botryoides.

Prenatal ultrasound can be useful in identifying a nasopharyngeal teratoma when there are signs of polyhydramnios secondary to pharyngeal obstruction. On CT and MR, these tumors are heterogeneous masses with cystic and solid components and in some cases associated calcifications. CT and MR are also important in helping to identify vascularity and intracranial extension. There may be signs of a long-standing lesion with mass effect on adjacent structures, especially distortion of the ipsilateral hemimandible and pterygoid plates.

Routine follow up is necessary for complete management. Patients should be evaluated for recurrence by physical examination and flexible nasopharyngoscopy, CT or MRI when indicated.

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