Teratoma

Teratoma of the oral and maxillofacial region is a rare germ cell neoplasm composed of tissues derived from all three embryonic germ layers—ectoderm, mesoderm, and endoderm—foreign to the anatomic site of origin.[1][2] These tumors arise from misplaced pluripotent embryologic germ cells, most likely primordial germ cells that become sequestered during their migration along the midline of the developing embryo.[3][4] The vast majority are congenital and present in the neonatal period as heterogeneous masses of the oropharynx, nasopharynx, palate, or cervical region.[1][5] Most head and neck teratomas are histologically mature and biologically benign, though immature and rarely malignant forms occur.[6][7] The characteristic imaging pattern is a mixed solid-cystic mass containing fat, calcification, and occasionally tooth-like structures.[2][8] Complete surgical excision is the definitive treatment.[7][9]

Current Classification

Teratomas are classified within the germ cell tumor family. The WHO classification of germ cell tumors recognizes mature teratoma, immature teratoma, and teratoma with malignant transformation as distinct entities.[10] Immature teratomas are graded based on the proportion of immature neuroepithelial tissue: grade 1 (50%).[6][10] A two-tier system (low-grade and high-grade) is also in use.[11]

Accepted Names and Aliases

• Epignathus: a congenital teratoma arising from the hard palate, skull base, or pharynx and protruding through the oral cavity. This term is specific to the oropharyngeal/palatal location and is not synonymous with all head and neck teratomas.[12][13]
• Dermoid and epidermoid are distinct ectoderm-lined inclusion cysts and should not be confused with true teratomas, which by definition contain tissues from more than one germ layer.[2]

• Congenital teratomas at all sites occur in approximately 1 in 4,000 births.[6][13]
• Head and neck teratomas account for less than 6% of all pediatric teratomas, with an estimated incidence of 1 in 20,000–40,000 live births.[1][14]
• Epignathus (oropharyngeal teratoma) is rarer still, estimated at 1 in 35,000 to 1 in 200,000 live births.[13][15]
• Approximately 90% of head and neck teratomas present during the neonatal or infantile period.[14][16]
• The cervical region and nasopharynx/oropharynx are the most common head and neck sites. Involvement of the jaws (mandible or maxilla) is exceptionally rare, with only isolated case reports.[1][6][17]
• Sex predilection is inconsistent across series; some report a male predominance, while the largest multicenter cohort shows a female-to-male ratio of approximately 3:1 for germ cell tumors overall.[5][7]
• A bimodal age distribution has been described: neonatal teratomas are overwhelmingly benign, whereas those presenting in later childhood or adulthood carry a higher risk of malignancy.[6][10]

Presentation and Symptoms

• Neonatal presentation is typical. Congenital teratomas of the oral cavity and pharynx commonly present as a visible mass protruding from the mouth at birth. Cervical teratomas present as anterolateral neck masses.[5][13][18][19]
• Airway obstruction is the most critical complication, occurring in approximately one-third to over half of neonates with congenital head and neck teratomas. Respiratory distress may be immediately life-threatening.[7]
• Feeding difficulty is common with oropharyngeal lesions.[15][18]
• Polyhydramnios in utero is a frequent prenatal finding, resulting from impaired fetal swallowing.[1][19]
• Prenatal diagnosis is achieved in roughly half of oropharyngeal and cervical cases via fetal ultrasound and MRI.[5][7]

Associated Anomalies

• Cleft palate is the most commonly reported associated malformation.[18][20]
• Other reported associations include bifid tongue, dorsonasal fistula, nasal dermoid cyst, and rarely mandibular or pituitary duplication.[20][21]
• Intracranial extension from skull base teratomas occurs occasionally and warrants evaluation.[12][22]

Noncongenital Presentation

Rarely, teratomas of the jaws present in later childhood as painless or painful swelling with displacement of dentition, without airway compromise.[1][6] These noncongenital cases are exceedingly uncommon and may mimic odontogenic tumors clinically.

Location and Distribution

• Oral and maxillofacial teratomas most commonly arise from the oropharynx, nasopharynx, or hard palate (epignathus), with attachment to the palate, sphenoid bone, or skull base.[12][23]
• Cervical teratomas originate in the anterolateral neck.[5][19]
• Primary intraosseous teratomas of the mandible or maxilla are exceptionally rare; reported sites include the mandibular body and the maxillary sinus.[1][6]

Periphery and Shape

• Teratomas are characteristically multiloculated, often large, and irregularly shaped.[2]
• Mature teratomas may appear well-circumscribed or encapsulated.[1]
• Immature or malignant teratomas tend to have more obscure margins and may show evidence of local invasion.[6][24]

Internal Architecture

The hallmark of teratoma on imaging is internal heterogeneity reflecting the diverse tissue composition:[2][8]

• Fat is nearly pathognomonic and appears as areas of low attenuation on CT. Fat may manifest as radiolucent foci on conventional radiographs when present in sufficient quantity.[8][25]
• Calcification is a characteristic finding, ranging from punctate or globular calcifications to well-formed tooth-like structures (odontoid structures). Tooth-like calcifications within a mass are highly suggestive of teratoma.[21][25][26][27]
• Cystic components are common, particularly in mature teratomas, which tend to be predominantly cystic. Immature teratomas are more solid with smaller cystic areas.[19][22][28]
• A combination of solid and cystic components is the most frequent overall pattern.[8][19]
• Bone or cartilage elements may be identified within the mass.[23][25]

Effects on Teeth and Adjacent Structures

• Oropharyngeal teratomas may displace developing tooth buds and deform the palate.[21][29]
• Intraosseous jaw teratomas produce a destructive, multiloculated radiolucent lesion with displacement of dentition and expansion of the mandible or maxilla.[1]
• Maxillary sinus teratomas may erode the orbital floor, medial maxillary wall, and invade the pterygopalatine fossa and masticator space.[6]
• Cervical teratomas can compress and displace the trachea and esophagus.[5][19]

Growth Pattern and Cortical Involvement

• Teratomas may grow rapidly, particularly in late gestation.[19]
• Intraosseous lesions produce cortical expansion and destruction with an aggressive radiographic appearance that may mimic malignancy.[1]
• Skull base erosion and extension into the nasal cavity, orbits, or intracranial compartment occur occasionally with large palatal or nasopharyngeal teratomas.[6][12][30]

Variant Imaging Patterns

• Small benign facial teratomas may lack calcification, hemorrhage, or increased vascularity, making radiographic diagnosis difficult.[19]
• Intratumoral hemorrhage and necrosis, when present, raise concern for malignancy.[19]
• Highly differentiated mature teratomas may rarely contain identifiable organoid structures or fetal parts.[19]

MRI Signal Characteristics

MRI is the primary advanced imaging modality for characterizing head and neck teratomas and assessing their relationship to the airway and adjacent structures:[19][31]

• Teratomas typically demonstrate mixed signal intensity on both T1- and T2-weighted sequences, reflecting their heterogeneous tissue composition.[19][22]
• Fat components show high signal on T1-weighted images and lose signal on fat-suppressed sequences, providing a near-pathognomonic finding.[19]
• Cystic components are T2-hyperintense and T1-hypointense.[22]
• Solid components of immature teratomas may show restricted diffusion (high DWI signal), corresponding to immature neuroepithelial elements.[22][32]
• Mature teratomas show minimal or no enhancement of cyst walls; immature and malignant teratomas demonstrate heterogeneous or ring-like enhancement of solid portions.[33]

MRI for Airway Assessment

• Prenatal and postnatal MRI is critical for evaluating airway patency, tracheal displacement, and the relationship of the mass to the fetal swallowing mechanism.[19][31]
• The tracheoesophageal displacement index (TEDI) measured on MRI is an emerging predictive tool for airway risk and need for EXIT procedure.[9][31]

CT

• Medical CT delineates calcification, fat, bone, and tooth-like structures with high spatial resolution and is valuable for preoperative planning of jaw and skull base lesions.[34]
• CT characteristics specific to benign cystic teratomas include a predominantly fatty mass with a denser dependent element and globular calcification, bone, or teeth projecting into the cyst cavity.[25]
• Malignant teratomas are predominantly solid on CT, with calcification and fat present less frequently than in benign lesions.[28]

Ultrasound

• Prenatal ultrasound is the initial modality for detection, demonstrating a heterogeneous mass with mixed echogenicity, and may identify calcifications and vascularity.[35][36]

Teratomas of the oral and maxillofacial region must be distinguished from other congenital and pediatric masses that present in similar locations. The presence of fat, calcification, and tooth-like structures within a heterogeneous mass is highly suggestive, but not all teratomas display these features, and biopsy is often required.[1][19]

The highest-risk diagnostic pitfall is misidentifying a malignant germ cell tumor component (yolk sac tumor or embryonal carcinoma) within what appears to be a benign teratoma. Serum alpha-fetoprotein measurement and incisional biopsy with thorough histopathologic sampling are essential to exclude malignant elements, particularly in lesions presenting beyond the neonatal period.[6][17][40]

Diagnostic Microscopic Findings

• By definition, teratomas contain tissues from all three germ layers:[1][3]
  • Ectodermal: keratinizing squamous epithelium, skin with pilosebaceous units, neural tissue
  • Mesodermal: adipose tissue, cartilage, bone, smooth and skeletal muscle, fibrous tissue
  • Endodermal: respiratory columnar epithelium, glandular intestinal-type epithelium, hepatic tissue
• Neuroectodermal elements are present in the majority of head and neck teratomas.[1]

Mature vs. Immature Teratoma

• Mature teratomas contain fully differentiated, adult-type tissues and are considered benign.[1][17]
• Immature teratomas contain embryonal or fetal-type tissue, predominantly immature neuroepithelium. Grading is based on the proportion of immature neuroepithelial tissue. In children, immature teratomas generally behave in a benign fashion despite histologic immaturity, though they carry a risk of decreased event-free survival compared with mature teratomas.[6][10][17]
• Approximately 20–40% of benign pediatric teratomas contain some immature elements.[6]

Malignant Components

• Malignant germ cell elements (yolk sac tumor, embryonal carcinoma, choriocarcinoma) may coexist within a teratoma, constituting a mixed malignant germ cell tumor. This occurs in a small minority of head and neck cases.[7][40]
• Incomplete resection of a teratoma may be followed by recurrence as an endodermal sinus tumor, underscoring the importance of complete excision and surveillance.[17]

Radiologic-Pathologic Correlation

• Fat on imaging corresponds to mature adipose tissue histologically.[8][25]
• Calcifications and tooth-like structures correspond to bone, cartilage, and dental hard tissue elements.[21][26]
• Solid components with restricted diffusion on MRI correlate with immature neuroepithelial elements.[22]
• Predominantly cystic architecture on imaging corresponds to mature histology; predominantly solid architecture suggests immature or malignant components.[19][28]

Prenatal Planning

• Prenatal diagnosis via fetal ultrasound and MRI enables multidisciplinary birth planning.[5][9]
• The EXIT (ex utero intrapartum treatment) procedure is indicated when prenatal imaging demonstrates airway compromise, allowing controlled airway management while maintaining fetoplacental circulation. Congenital teratoma is the leading indication for EXIT, accounting for nearly half of all EXIT procedures.[5][7][9]

Definitive Treatment

• Complete surgical excision is the standard of care for all head and neck teratomas.[1][7][9]
• Early surgical resection is recommended, typically within the first days to weeks of life for congenital lesions.[7][41]
• Complete resection is achieved in the majority of cases with a single surgery. Cervical teratomas are generally more amenable to complete resection than pharyngeal teratomas.[7]
• For intraosseous jaw teratomas, resection may require segmental mandibulectomy or maxillectomy with reconstruction.[1]

Recurrence and Surveillance

• Recurrence is rare when complete resection is achieved. Incomplete resection is the primary risk factor for recurrence.[1][5][7][20][41]
• The overall local recurrence rate in a large multicenter cohort was approximately 2.6%.[7]
• Alpha-fetoprotein (AFP) should be monitored postoperatively every 2–3 months to detect recurrence or malignant transformation.[6][7][42]
• Clinical examination and imaging every 3 months during the first 2 years is recommended for benign tumors; malignant tumors require imaging and AFP measurement at the same interval.[7]

Prognosis

• The overall prognosis for neonatal head and neck teratomas is excellent, with mortality now estimated at approximately 1–2% in centers with modern multidisciplinary management including EXIT capability.[7]
• Risk factors for poor outcome include large unresectable tumors, severe airway compromise without prenatal diagnosis, and malignant histologic components.[7][17]
• Adult head and neck teratomas carry a substantially worse prognosis.