Diagnostic Imaging in Veterinary Dental Practice

Ashley Nichter 1College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.

Search for other papers by Ashley Nichter in
Current site
Google Scholar
PubMed
Close
 BS
,
Santiago Peralta 2Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.

Search for other papers by Santiago Peralta in
Current site
Google Scholar
PubMed
Close
 DVM
, and
Nadine Fiani 2Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.

Search for other papers by Nadine Fiani in
Current site
Google Scholar
PubMed
Close
 BVSc

History and Physical Examination Findings

A 2.5-year-old spayed female domestic shorthair cat was evaluated at the dentistry and oral surgery service of a veterinary teaching hospital because of an oral mass located in the right maxillary canine tooth region that had been present since birth. Six months prior to this examination, the referring veterinarian surgically debulked the mass and extracted the right maxillary canine tooth, and tissue samples were submitted for histologic examination. Findings included the presence of disorganized odontogenic epithelium intermixed with stroma; minimal nuclear variation was reported. Ameloblastic fibroma was diagnosed on the basis of the predominant epithelial component of the mass. Approximately 1 month after the initial procedure, the mass recurred clinically and continued to grow over the next 6 months. The patient then developed progressively more evident inspiratory stertor and decreased appetite.

Oral examination of the conscious cat at the veterinary teaching hospital revealed gingival enlargement at the level of the previously extracted right maxillary canine tooth. The gingiva appeared firm, pink, and well circumscribed, and palpation did not elicit signs of pain. The hard palate immediately medial to the enlarged gingiva appeared to be slightly ventrally deviated; aside from signs of mild periodontal disease, the remaining physical examination results were unremarkable. Results of a CBC and serum biochemical analysis were within the respective reference ranges. With the patient under general anesthesia, a clinical photograph and an intraoral radiograph of the rostral portion of the maxilla were obtained (Figures 1 and 2).

Figure 1—
Figure 1—

Photograph showing the rostral maxillary region of a 2.5-year-old cat that was referred to the dentistry and oral surgery service of a veterinary teaching hospital for examination because of a recurrent mass in the right maxillary canine tooth region, inspiratory stertor, and decreased appetite. The image was obtained with the cat in dorsal recumbency. There is gingival enlargement at the level of the previously extracted right maxillary canine tooth. Notice the subtle ventral deviation of the palatal mucosa medial to the abnormal gingiva.

Citation: Journal of the American Veterinary Medical Association 256, 5; 10.2460/javma.256.5.553

Figure 2—
Figure 2—

Intraoral occlusal radiograph of the rostral portion of the maxilla of the cat in Figure 1. The image was obtained with a size-4 phosphor plate.

Citation: Journal of the American Veterinary Medical Association 256, 5; 10.2460/javma.256.5.553

Determine whether additional studies are required, or make your diagnosis, then turn the page

Diagnostic Imaging Findings and Interpretation

The intraoral occlusal radiograph of the rostral aspect of the maxilla revealed a large and well-demarcated lesion that affected the maxilla and resulted in loss of nasal turbinate detail (Figure 3). The lesion extended from the rostral aspect of the right maxilla to the level of the right maxillary fourth premolar tooth with the most rostral aspect reaching midline. To better document the nature, size, and extent of the mass, CT of the patient's head and neck was performed with and without contrast medium. The images were acquired with 0.5-mm slice thickness in the transverse plane and were reconstructed in sagittal and dorsal planes with a bone algorithm (window width, 4,500 HU; window level, 1,100 HU; Figure 4). The images revealed a large, expansile soft tissue mass that encompassed the right nasal cavity, crossed the midline, and invaded the ventral aspect of the left nasal cavity. Caudally, the mass extended as a thin and well-demarcated soft tissue mass that occluded the nasopharynx. A second biopsy of the mass was performed during the same anesthetic episode and submitted for histologic analysis. The results confirmed the diagnosis of ameloblastic fibroma (Figure 5). Further staging was not pursued, given the typically benign biological behavior of ameloblastic fibromas.1

Figure 3—
Figure 3—

Same radiographic image as in Figure 2. A well-demarcated area with evidence of bone loss and absence of turbinate detail extends from the level of the right maxillary canine tooth alveolus to the level of the right maxillary fourth premolar tooth (arrowheads). Lateral deviation of the nasal septum (white arrow), attributable to the expansile effect of the mass, is present. Given the 2-D nature of the intraoral radiograph, it is not possible to assess the dorsoventral extent of the lesion.

Citation: Journal of the American Veterinary Medical Association 256, 5; 10.2460/javma.256.5.553

Figure 4—
Figure 4—

Representative non–contrast-enhanced CT images of the head of the cat in Figure 1, viewed with a bone algorithm. A—A transverse-plane image obtained at the level of the maxillary first molar tooth reveals complete obstruction of the nasopharynx by the soft tissue mass (asterisk). B—A reconstructed dorsal-plane image at the level of the nasal cavity shows the soft tissue mass in the right nasal cavity with evidence of lysis of the nasal conchae (arrow). The mass extends caudally into the nasopharynx (asterisk). C—A reconstructed sagittal-plane image close to the patent's midline reveals the dorsal extent of the lesion within the nasal cavity (arrow) and its caudal extent within the nasopharynx (asterisk).

Citation: Journal of the American Veterinary Medical Association 256, 5; 10.2460/javma.256.5.553

Figure 5—
Figure 5—

Photomicrograph of a biopsy specimen of the oral mass in the cat in Figure 1. Islands of small, polygonal epithelial cells (arrows) are entrapped within tracts of loose fibrous connective tissue embedded within evenly spaced, stellate spindle cells resembling ectomesenchyme. Differentiation reminiscent of the cap stage of odontogenesis is not evident, and there is a lack of calcified matrix including dentin, enamel, stroma, or bone and a lack of bony invasion, which would have been more consistent with feline inductive odontogenic tumor. The findings confirmed a previous diagnosis of feline ameloblastic fibroma. H&E stain; bar = 200 μm.

Citation: Journal of the American Veterinary Medical Association 256, 5; 10.2460/javma.256.5.553

Treatment and Outcome

Owing to the size of the tumor and its extensive invasion into the nasal cavity, complete marginal excision was not considered technically feasible. Radiation therapy to reduce the size of the tumor and minimize signs associated with airway obstruction was offered but declined. The cat was prescribed meloxicam (0.1 mg/kg [0.05 mg/lb], PO) and buprenorphine (0.02 mg/kg [0.009 mg/lb], transmucosally, q 12 h) as palliative measures to reduce inflammation and provide analgesia. The cat was reexamined 2 weeks later and was reportedly more comfortable with the prescribed medications. Oral examination revealed that the biopsy site had healed well.

Comments

Odontogenic tumors occur in several mammalian species.2,3 Odontogenic tumors arise from tooth-associated epithelium, mesenchyme, or both.1,4 As with neoplasms in general, the biological behavior and metastatic potential of odontogenic tumors are greatly dependent on their histologic nature, which makes classification important in determining treatment options and prognosis.1 In contrast to the findings for dogs, odontogenic tumors are uncommon in cats, making up < 3% of all feline oral neoplasms, and the nomenclature used to describe these tumors is often confusing and inconsistent.5

The initial histologic diagnosis in this case was ameloblastic fibroma. Although the nomenclature is ambiguous, this tumor type and related lesions make up a group of neoplasms that have epithelial and mesenchymal components, with or without inductive properties.6 Ameloblastic fibromas are more often found in adult cats, typically > 6 years of age, and can develop in the mandible or maxilla.7 These are benign, slow-growing tumors with well-demarcated, encapsulated borders.8 Although these tumors do not usually deeply infiltrate surrounding tissues, they can cause local tissue destruction by a space-occupying mechanism if left untreated. The neoplasm described as feline inductive odontogenic tumor has been proposed as a unique tumor type in cats and is often misclassified as ameloblastic fibroma.1 However, the biological behavior and histologic features of these 2 tumors differ. In contrast to ameloblastic fibromas, feline inductive odontogenic tumors are typically found in cats < 3 years of age and generally develop in the rostral aspect of the maxilla.9 Feline inductive odontogenic tumors are also infiltrative neoplasms with indistinct borders and are more likely to cause direct destruction of adjacent bone.8 Given our patient's signalment and history, it was prudent to perform a second biopsy to confirm the original diagnosis.

Dental radiography and CT are both useful for evaluation of odontogenic tumors. Dental radiographs are important for assessing intraoral expansion of the lesions and the presence and severity of tissue destruction. Ameloblastic fibromas are characteristically well-demarcated, single-cavity radiolucencies within a jaw.6 As these tumors become larger, dental radiography may reveal destruction of surrounding teeth. Extraoral expansion of these tumors is best evaluated by CT, and this was particularly important for the cat of the present report because severe inspiratory stertor was present. If excision is being considered, obtaining CT images in addition to intraoral radiographs is valuable for strategic surgical planning. Although specific imaging characteristics rely somewhat on the classification, odontogenic tumors are generally associated with the dentate region of the jaw, result in bony lysis, and can be variably soft tissue attenuating to mineral attenuating on CT images.10

Although benign and slow-growing, ameloblastic fibromas have high rates of recurrence if incompletely excised.11 If the goal of treatment is long-term remission without recurrence, wide en bloc excision including underlying bone is recommended.11 In the case described here, wide surgical excision was not possible because of the extent of the mass, and conservative treatment options could have been pursued for a more palliative approach. Tumor debulking procedures followed by palliative radiation therapy protocols for the treatment of odontogenic tumors in cats have been reported to prolong the progression-free interval for up to 2 years.12 Radiation therapy can also be considered in cases of tumor recurrence or can be provided as adjunctive treatment after initial surgical intervention in patients with incompletely excised odontogenic tumors.

The prognosis for cats with odontogenic tumors relies greatly on the histologic diagnosis because biological behavior and metastatic potential vary greatly among these tumors. However, given the complex architecture of the oral, dental, and maxillofacial structures, prognostication also requires determination of the extent of disease for consideration of realistic therapeutic approaches. Dental radiography and CT are vital diagnostic resources in these cases, as they provide information regarding the involvement of teeth and bony structures and can be used to guide surgical or radiation treatment planning.

Acknowledgments

Ashley Nichter was a third-year veterinary student at the time of manuscript submission.

The authors thank Kathleen Kelly, Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, for providing the photomicrograph and histologic description of the tumor.

References

  • 1. Bell CM, Soukup JW. Nomenclature and classification of odontogenic tumors—part II: clarification of specific nomenclature. J Vet Dent 2014;31:234243.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 2. Soukup JW, Bell CM. Nomenclature and classification of odontogenic tumors—part I: historical review. J Vet Dent 2014;31:228232.

  • 3. Walsh KM, Denholm LJ, Cooper BJ. Epithelial odontogenic tumours in domestic animals. J Comp Pathol 1987;97:503521.

  • 4. Wright JM, Vered M. Update from the 4th edition of the World Health Organization classification of head and neck tumours: odontogenic and maxillofacial bone tumors. Head Neck Pathol 2017;11:6877.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 5. Stebbins KE, Morse CC, Goldschmidt MH. Feline oral neoplasia: a ten-year survey. Vet Pathol 1989;26:121128.

  • 6. Chen Y, Li T, Gao Y, et al. Ameloblastic fibroma and related lesions: a clinicopathologic study with reference to their nature and interrelationship. J Oral Pathol Med 2005;34:588595.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 7. Gardner DG. Ameloblastomas in cats: a critical evaluation of the literature and the addition of one example. J Oral Pathol Med 1998;27:3942.

    • Search Google Scholar
    • Export Citation
  • 8. Liu DX, Doyle LA, Bouljihad MT. Locally infiltrative ameloblastic fibroma in a rhesus macaque (Macaca mulatta) with characterizations of its proliferating activity and biological behavior. J Vet Diagn Invest 2012;24:630635.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 9. Gardner DG, Dubielzig RR. Feline inductive odontogenic tumor (inductive fibroameloblastoma)—a tumor unique to cats. J Oral Pathol Med 1995;24:185190.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 10. Amory JT, Reetz JA, Sánchez MD, et al. Computed tomographic characteristics of odontogenic neoplasms in dogs. Vet Radiol Ultrasound 2014;55:147158.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 11. Dernell WS, Hullinger GH. Surgical management of ameloblastic fibroma in the cat. J Small Anim Pract 1994;35:3538.

  • 12. Moore AS, Wood CA, Engler SJ, et al. Radiation therapy for long-term control of odontogenic tumours and epulis in three cats. J Feline Med Surg 2000;2:5760.

    • Crossref
    • Search Google Scholar
    • Export Citation

Contributor Notes

Address correspondence to Dr. Fiani (nf97@cornell.edu).
  • Figure 1—

    Photograph showing the rostral maxillary region of a 2.5-year-old cat that was referred to the dentistry and oral surgery service of a veterinary teaching hospital for examination because of a recurrent mass in the right maxillary canine tooth region, inspiratory stertor, and decreased appetite. The image was obtained with the cat in dorsal recumbency. There is gingival enlargement at the level of the previously extracted right maxillary canine tooth. Notice the subtle ventral deviation of the palatal mucosa medial to the abnormal gingiva.

  • Figure 2—

    Intraoral occlusal radiograph of the rostral portion of the maxilla of the cat in Figure 1. The image was obtained with a size-4 phosphor plate.

  • Figure 3—

    Same radiographic image as in Figure 2. A well-demarcated area with evidence of bone loss and absence of turbinate detail extends from the level of the right maxillary canine tooth alveolus to the level of the right maxillary fourth premolar tooth (arrowheads). Lateral deviation of the nasal septum (white arrow), attributable to the expansile effect of the mass, is present. Given the 2-D nature of the intraoral radiograph, it is not possible to assess the dorsoventral extent of the lesion.

  • Figure 4—

    Representative non–contrast-enhanced CT images of the head of the cat in Figure 1, viewed with a bone algorithm. A—A transverse-plane image obtained at the level of the maxillary first molar tooth reveals complete obstruction of the nasopharynx by the soft tissue mass (asterisk). B—A reconstructed dorsal-plane image at the level of the nasal cavity shows the soft tissue mass in the right nasal cavity with evidence of lysis of the nasal conchae (arrow). The mass extends caudally into the nasopharynx (asterisk). C—A reconstructed sagittal-plane image close to the patent's midline reveals the dorsal extent of the lesion within the nasal cavity (arrow) and its caudal extent within the nasopharynx (asterisk).

  • Figure 5—

    Photomicrograph of a biopsy specimen of the oral mass in the cat in Figure 1. Islands of small, polygonal epithelial cells (arrows) are entrapped within tracts of loose fibrous connective tissue embedded within evenly spaced, stellate spindle cells resembling ectomesenchyme. Differentiation reminiscent of the cap stage of odontogenesis is not evident, and there is a lack of calcified matrix including dentin, enamel, stroma, or bone and a lack of bony invasion, which would have been more consistent with feline inductive odontogenic tumor. The findings confirmed a previous diagnosis of feline ameloblastic fibroma. H&E stain; bar = 200 μm.

  • 1. Bell CM, Soukup JW. Nomenclature and classification of odontogenic tumors—part II: clarification of specific nomenclature. J Vet Dent 2014;31:234243.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 2. Soukup JW, Bell CM. Nomenclature and classification of odontogenic tumors—part I: historical review. J Vet Dent 2014;31:228232.

  • 3. Walsh KM, Denholm LJ, Cooper BJ. Epithelial odontogenic tumours in domestic animals. J Comp Pathol 1987;97:503521.

  • 4. Wright JM, Vered M. Update from the 4th edition of the World Health Organization classification of head and neck tumours: odontogenic and maxillofacial bone tumors. Head Neck Pathol 2017;11:6877.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 5. Stebbins KE, Morse CC, Goldschmidt MH. Feline oral neoplasia: a ten-year survey. Vet Pathol 1989;26:121128.

  • 6. Chen Y, Li T, Gao Y, et al. Ameloblastic fibroma and related lesions: a clinicopathologic study with reference to their nature and interrelationship. J Oral Pathol Med 2005;34:588595.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 7. Gardner DG. Ameloblastomas in cats: a critical evaluation of the literature and the addition of one example. J Oral Pathol Med 1998;27:3942.

    • Search Google Scholar
    • Export Citation
  • 8. Liu DX, Doyle LA, Bouljihad MT. Locally infiltrative ameloblastic fibroma in a rhesus macaque (Macaca mulatta) with characterizations of its proliferating activity and biological behavior. J Vet Diagn Invest 2012;24:630635.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 9. Gardner DG, Dubielzig RR. Feline inductive odontogenic tumor (inductive fibroameloblastoma)—a tumor unique to cats. J Oral Pathol Med 1995;24:185190.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 10. Amory JT, Reetz JA, Sánchez MD, et al. Computed tomographic characteristics of odontogenic neoplasms in dogs. Vet Radiol Ultrasound 2014;55:147158.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 11. Dernell WS, Hullinger GH. Surgical management of ameloblastic fibroma in the cat. J Small Anim Pract 1994;35:3538.

  • 12. Moore AS, Wood CA, Engler SJ, et al. Radiation therapy for long-term control of odontogenic tumours and epulis in three cats. J Feline Med Surg 2000;2:5760.

    • Crossref
    • Search Google Scholar
    • Export Citation

Advertisement