Abstract
Teratomas originate from pluripotent germ cells and differentiate into the 3 germ cell layers: endoderm, mesoderm, and ectoderm. Hence, these tumors arise most often in the gonads. Extragonadal teratomas are rare in veterinary medicine. Congenital oropharyngeal teratoma, also known as epignathus, is a neoplasm that has been reported in humans and a few veterinary species. We describe the clinical, gross, cytologic, and histopathologic features of an oropharyngeal teratoma in a neonatal Boer × Nigerian Dwarf goat that died within 4 h of birth, and briefly review extragonadal teratomas in veterinary species.
Congenital neoplasms are classified as neoplastic lesions that are detectable at birth or within the first 2 mo of life. 26 They are still considered congenital even if identified up to 2 mo into the postnatal period, provided their origin can be traced back to embryonic development. 26 Although rare, a wide range of congenital neoplasms have been sporadically reported across domestic species, including pigs, 27 horses, 28 cattle,18,25,26,46 dogs, 43 and cats. 42
Congenital neoplasms are considered rare in small ruminants. 44 Our search of PubMed using search terms “goat” OR “sheep” OR “small ruminant” AND “congenital” AND “tumor” yielded 11 results, of which 1 matched the criteria. The same search in Google identified 4 additional cases of congenital neoplasms, confirming that this condition is rarely reported. The 5 cases identified included a fetal rhabdomyoma in a stillborn Ardi goat kid, 2 an intracranial teratoma in a 1-d-old lamb, 34 a cutaneous hemangioma in a 5-d-old lamb, 3 an intradural melanoma in a 9-d-old Saanen goat kid, 44 and an extraneural hemangioblastoma in a 1-mo-old lamb. 51
A 2.54-kg, 4-h-old, female Boer × Nigerian dwarf kid was noted by the owner to be weak and non-suckling since birth. On presentation to the University of California, Davis, Veterinary Medical Teaching Hospital (Davis, CA, USA), the lamb was dyspneic, had marked respiratory acidosis, and lacked the suckle reflex. Thoracic ultrasound revealed aspiration pneumonia, particularly affecting the cranioventral lung fields. During attempts at intravenous catheter placement, the animal experienced cardiac arrest and could not be resuscitated. Laryngoscopy performed during cardiopulmonary resuscitation by the submitting clinicians identified a large, firm nodule located in the caudal soft palate, suspected to be obstructing the airway.
A routine autopsy was performed. Grossly, an expansile, well-demarcated, 2 × 1.5 × 1-cm mass nearly completely filled and occluded the oropharynx and extended into the caudal aspect of the nasopharynx (
Gross, cytologic, and histologic features of a congenital oropharyngeal teratoma in a neonatal goat.
A wide variety of cells exfoliated in impression smears of the mass (
Histologically, the periphery of the mass was covered circumferentially by haired skin with an epidermis and dermis that had loosely arranged collagen with numerous blood vessels, brown adipose tissue, hair follicles, and sebaceous and apocrine glands (
Teratomas are congenital tumors that arise from pluripotent germ cells. 7 At least 2 embryonic germ layers (ectoderm, mesoderm, endoderm) are present; teratomas therefore arise most often in the gonads (ovaries and testes). 7 Extragonadal teratomas are rare in veterinary medicine. Cases of congenital oropharyngeal teratomas have been reported in humans, 36 cats,32,52 a sable antelope, 12 and potentially a calf. 1 Congenital orofacial teratomas are also called epignathus and can rarely extend into the cranium in affected neonates. 21 The cell(s) of origin for oropharyngeal teratomas is unknown. However, pluripotent cells in the notochord during early embryogenesis or in the region of Rathke pouch are hypothesized as potential candidates.19,33 Other congenital oral neoplasms affecting the gingiva and lip have been reported in domestic species (e.g., squamous cell carcinoma in a pig 13 and hemangiosarcoma in a foal 9 ). For a congenital oropharyngeal mass, teratoma should be considered a possibility.
A notable species in which extragonadal teratomas have been reported is the cat (9 of 41 cases, 22%;
Location, species, and age of animals diagnosed with extragonadal teratoma reported in the literature.
In people, teratomas are the most common extragonadal germ cell tumor in the prepubertal age group, and common sites of origin include the sacrococcygeal, intracranial, mediastinal, head, and peritoneal regions, 39 similar to descriptions in animals. Prognosis or age at presentation seems to be related to location and speed of growth. Most animals with an oropharyngeal teratoma were presented neonatally because of the obstructive nature of the mass. Similarly, animals with an intracranial teratoma were presented at a young age, apart from a 4-y-old alpaca with a teratoma that mostly expanded the meninges. 14 The neonatal kid in our case survived for 4 h and received medical attention. If the mass had not completely obstructed the nasopharyngeal space, surgical excision may have been an option.
Footnotes
Acknowledgements
We thank the client and clinicians, especially Drs. Frances Fan and Munashe Chigerwe, at the University of California, Davis, Veterinary Medical Teaching Hospital, for submitting this case to the pathology service, and the Histology Lab for the quality slides and staining. We thank Dr. Jiyoon Lee for reviewing the manuscript.
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
