History
A 1-year-old 31.6-kg castrated male Labrador Retriever was presented for shortness of breath, inappetence, and a progressive swelling on the left side of his muzzle beneath his eye. The swelling had been present for 5 weeks and was initially thought to be related to an insect sting. A punch biopsy of the swelling was performed. Results were consistent with a highly necrotic and fragmented lymph node with no identifiable underlying cause. A Periodic acid–Schiff fungal stain was added to the sample, and no fungal organisms were identified. The dog was discharged with carprofen (150 mg, PO, q 24 h) and cefpodoxime (300 mg, PO, q 24 h). While on antimicrobial therapy he developed intermittent left-sided epistaxis which continued over the following 2 weeks despite extended antimicrobial treatment and addition of Yunnan Baiyao (500 mg, PO, q 12 h). The swelling beneath the dog’s left eye became progressively larger, and his owners also noticed that he was becoming more depressed, inappetent, and painful.
On presentation the dog was bright, alert, and responsive. Body temperature was elevated at 40.6 °C. Heart rate and respiratory rate were within normal limits, and there were no abnormalities appreciated on thoracic auscultation. Mild, bilateral, mucoid ocular discharge was present. There was serosanguinous discharge coming from the left nostril with absent left airway patency. There was a warm soft tissue swelling on the left side of the head extending from beneath the left eye to the nasal planum. On oral exam, moderate, regional periodontal inflammation with moderate to severe dental calculus was identified along the left maxillary arcade, and the upper third premolar (207) was notably loose. There was also a focal, firm swelling palpable along the buccal mucosa adjacent to 207/208, and the left mandibular lymph node was enlarged. The remainder of the dog’s physical exam was within normal limits.
Initial blood gas analysis showed evidence of mild dehydration, with a PCV of 44%, and total solids at 7.1 g/dL. CBC revealed a mild monocytosis (1360 cells/µL; reference range, 0 to 840) and the serum biochemistry panel was overall unremarkable with only a mild decrease in CPK (50 IU/L; reference range, 59 to 895).
An impression smear of the nasal discharge was performed and showed degenerate neutrophils which were too numerous to count and intracellular coccobacilli. A sample of the dog’s nasal discharge was submitted for aerobic culture and antimicrobial sensitivity. The final culture report showed moderate growth of Pasteurella species, with few colonies of both Actinomyces species and Moraxella species also present. No resistance was seen on antimicrobial sensitivity.
The dog was transferred from the emergency and critical care service to the internal medicine service for further diagnostics, which included CT and possible rhinoscopy. CT images of the head (LightSpeed VCT 64-Slice; General Electric) were obtained pre- and post-intravenous contrast (Omnipaque; GE Healthcare; 300mgI/mL; Figure 1). Images are displayed in a bone and soft tissue window.
Transverse plane CT images of a 1-year-old castrated male Labrador Retriever dog at the level of the rostral maxillary premolars (A), cribriform plate (B), caudal maxillary premolars (C), and maxillary molars (D). Panels A and B show post-contrast images displayed in a soft tissue algorithm (window width, 250 HU; window level, 50 HU) with a slice thickness of 2.5 mm. Panels C and D show post-contrast images displayed in a bone algorithm (window width, 1,000 HU; window level, 250 HU) with a slice thickness of 2.5 mm. L = Left.
Citation: Journal of the American Veterinary Medical Association 261, 6; 10.2460/javma.22.10.0481
Transverse plane CT images of a 1-year-old castrated male Labrador Retriever dog at the level of the rostral maxillary premolars (A), cribriform plate (B), caudal maxillary premolars (C), and maxillary molars (D). Panels A and B show post-contrast images displayed in a soft tissue algorithm (window width, 250 HU; window level, 50 HU) with a slice thickness of 2.5 mm. Panels C and D show post-contrast images displayed in a bone algorithm (window width, 1,000 HU; window level, 250 HU) with a slice thickness of 2.5 mm. L = Left.
Citation: Journal of the American Veterinary Medical Association 261, 6; 10.2460/javma.22.10.0481
Transverse plane CT images of a 1-year-old castrated male Labrador Retriever dog at the level of the rostral maxillary premolars (A), cribriform plate (B), caudal maxillary premolars (C), and maxillary molars (D). Panels A and B show post-contrast images displayed in a soft tissue algorithm (window width, 250 HU; window level, 50 HU) with a slice thickness of 2.5 mm. Panels C and D show post-contrast images displayed in a bone algorithm (window width, 1,000 HU; window level, 250 HU) with a slice thickness of 2.5 mm. L = Left.
Citation: Journal of the American Veterinary Medical Association 261, 6; 10.2460/javma.22.10.0481
Formulate differential diagnoses, then continue reading.
Diagnostic Imaging Findings and Interpretation
There is a large, ill-defined, soft tissue attenuating mass lesion on the left side of the face that is heterogeneously contrast-enhancing and rim-enhancing and extends from the nasal planum to the caudal aspect of the left retrobulbar space. This lesion further extends laterally from the left maxilla and caudally along frontal bone into the left nasal passage, occluding the nasal passage and causing deviation of the nasal septum to the right. This is accompanied by marked turbinate destruction. Mild left globe exophthalmos is seen secondary to mass extension into the retrobulbar space. There are multifocal and extensive areas of osteolysis present, particularly affecting the left maxillary bone around the tooth roots, as well as gas trapping at the level of the premolar teeth. Focal areas of osteolysis extend to the oral cavity and left nasal passage. There is fluid attenuation and a small air-fluid interface occluding the left frontal sinus. The cribriform plate is intact and there is no evidence of a falx shift (Figure 2). Additional findings included moderately enlarged left mandibular lymph nodes (one with rim-enhancement and central hypoattenuation) and mild enlargement of the left medial retropharyngeal lymph node (Figure 3).
Same images and imaging parameters as Figure 1. A—Contrast-enhancing soft tissue and fluid attenuation occluding the left nasal cavity (carat) and extension of the contrast enhancing mass lesion outside of the nasal cavity (hashtag). B—Soft tissue attenuation of the left frontal sinus (asterisk), which represents extension of the lesion into the frontal sinus, fluid congestion, or both. Also visible in this image is a circular, rim-enhancing mass effect within the left retrobulbar space (dagger). C—Gas-trapping and bone lysis at the level of the maxillary premolar teeth (207 and 208; arrow), destruction of the left turbinate structures, and right lateral deviation of the nasal septum. D—Extensive lysis of the bone around the left maxillary molars, including loss of the ventrolateral aspect of the maxillary bone and margination of the left maxillary sinus (arrowhead). L = Left.
Citation: Journal of the American Veterinary Medical Association 261, 6; 10.2460/javma.22.10.0481
Same images and imaging parameters as Figure 1. A—Contrast-enhancing soft tissue and fluid attenuation occluding the left nasal cavity (carat) and extension of the contrast enhancing mass lesion outside of the nasal cavity (hashtag). B—Soft tissue attenuation of the left frontal sinus (asterisk), which represents extension of the lesion into the frontal sinus, fluid congestion, or both. Also visible in this image is a circular, rim-enhancing mass effect within the left retrobulbar space (dagger). C—Gas-trapping and bone lysis at the level of the maxillary premolar teeth (207 and 208; arrow), destruction of the left turbinate structures, and right lateral deviation of the nasal septum. D—Extensive lysis of the bone around the left maxillary molars, including loss of the ventrolateral aspect of the maxillary bone and margination of the left maxillary sinus (arrowhead). L = Left.
Citation: Journal of the American Veterinary Medical Association 261, 6; 10.2460/javma.22.10.0481
Same images and imaging parameters as Figure 1. A—Contrast-enhancing soft tissue and fluid attenuation occluding the left nasal cavity (carat) and extension of the contrast enhancing mass lesion outside of the nasal cavity (hashtag). B—Soft tissue attenuation of the left frontal sinus (asterisk), which represents extension of the lesion into the frontal sinus, fluid congestion, or both. Also visible in this image is a circular, rim-enhancing mass effect within the left retrobulbar space (dagger). C—Gas-trapping and bone lysis at the level of the maxillary premolar teeth (207 and 208; arrow), destruction of the left turbinate structures, and right lateral deviation of the nasal septum. D—Extensive lysis of the bone around the left maxillary molars, including loss of the ventrolateral aspect of the maxillary bone and margination of the left maxillary sinus (arrowhead). L = Left.
Citation: Journal of the American Veterinary Medical Association 261, 6; 10.2460/javma.22.10.0481
Additional post-contrast transverse plane CT image of the same dog at the level of the tympanic bullae. Image is shown in a soft tissue algorithm (window width, 1,000 HU; window level, 250 HU) at a slice thickness of 2.5 mm. Notice the moderately enlarged, peripherally rim enhancing, and centrally hypoattenuating left mandibular lymph node (arrow). L = Left.
Citation: Journal of the American Veterinary Medical Association 261, 6; 10.2460/javma.22.10.0481
Additional post-contrast transverse plane CT image of the same dog at the level of the tympanic bullae. Image is shown in a soft tissue algorithm (window width, 1,000 HU; window level, 250 HU) at a slice thickness of 2.5 mm. Notice the moderately enlarged, peripherally rim enhancing, and centrally hypoattenuating left mandibular lymph node (arrow). L = Left.
Citation: Journal of the American Veterinary Medical Association 261, 6; 10.2460/javma.22.10.0481
Additional post-contrast transverse plane CT image of the same dog at the level of the tympanic bullae. Image is shown in a soft tissue algorithm (window width, 1,000 HU; window level, 250 HU) at a slice thickness of 2.5 mm. Notice the moderately enlarged, peripherally rim enhancing, and centrally hypoattenuating left mandibular lymph node (arrow). L = Left.
Citation: Journal of the American Veterinary Medical Association 261, 6; 10.2460/javma.22.10.0481
CT findings were most consistent with an aggressive, neoplastic process such as a sarcoma, including osteosarcoma, or a squamous cell carcinoma. Fungal osteomyelitis was considered less likely due to history, geographic location, and negative fungal stain. Enlargement of the facial lymph nodes was consistent with either metastatic neoplasia, reactivity, or both.
Treatment and Outcome
Isotonic crystalloid fluid therapy was started intravenously at 110 mL/h, in addition to ampicillin-sulbactam (50 mg/kg, q 8 h) and methadone (0.2 mg/kg, q 6 h). After the CT was performed and differential diagnoses and treatment options were presented to the owners, humane euthanasia was elected based on poor prognosis and quality of life concerns. Multiple punch biopsies, acquired post-euthanasia, were submitted for histopathology. Microscopic findings were consistent with a poorly differentiated sarcoma with a mitotic index of greater than 100 mitotic figures in 10 high powered fields and multifocal neoplasm necrosis. Histopathological differentials included a high-grade soft tissue sarcoma, histiocytic sarcoma, amelanotic melanoma, or a poorly productive osteosarcoma.
Comments
CT was integral in determining the cause of this dog’s condition. Possible differentials prior to CT imaging included an extra-oral or oral abscess secondary to a foreign body or an infected tooth root, followed by an abscessed mass, or less likely, fungal disease. An aggressive nasal tumor was not considered highly likely, especially considering this dog’s age. Furthermore, direct diagnostic tests up until this point had provided only evidence of infection and lymph node necrosis. Further visualization of the lesion was thus vital for diagnosis, and CT was an appropriate choice, as it is known to be a highly sensitive and accurate imaging tool for diagnosing nasal disease in dogs.1 The soft tissue attenuating mass within the nasal cavity and loss of normal turbinate structures were pertinent findings suggestive of infiltrative nasal disease; however, the multifocal and severe bone lysis, destruction of the nasal septum and lateral maxilla, the mass effect causing deviation of the nasal septum, and evidence of invasion into the retrobulbar space were also key features in this study and led to a very high degree of suspicion for neoplasia. In addition, the enlargement and rim-enhancement of the mandibular lymph node was particularly concerning for metastasis, as rim-enhancement or heterogenous uptake of contrast has been previously described as a feature of malignancy and metastasis in other forms of canine neoplasia.2 These features were important for narrowing the list of differentials and provided prognostic information which ultimately led to a decision of humane euthanasia. It is worth noting that a final histopathological diagnosis was still necessary in this case, as the described CT features alone are not specific for aggressive neoplasia. Fungal osteomyelitis within the nasal cavity also shares many of these features and commonly affects younger dogs, which certainly would have made it a plausible differential in this case had a fungal stain not already been used to rule it out prior to CT.3
Nasal and paranasal tumors make up close to 1% of all canine neoplasms, with dolichocephalic and large-breed dogs seemingly being diagnosed more frequently, and most dogs being diagnosed at an average age of 10 years-old. Even though young dogs are often not considered as likely to develop neoplasia, dogs less than 1 year of age have also been diagnosed with nasal tumors. Nasal sarcomas (including fibrosarcoma, osteosarcoma, and soft tissue sarcoma) are less frequently diagnosed than carcinomas, and account for approximately one third of diagnosed neoplasia.4 Clinical signs typically include unilateral or bilateral epistaxis or nasal discharge, sneezing, difficulty breathing, unwillingness to eat, chew, or open the mouth, regional swelling and pain, and possibly exophthalmos or ocular discharge.
Radiography is an acceptable way to evaluate the nasal cavity and sinuses in dogs with upper respiratory signs and can even help to determine extensiveness of a lesion in some cases where there is bony lysis of the maxilla.5 However, while digital radiographs can be more cost effective, 2-D imaging also has limitations, and cross-sectional imaging via CT or MRI ultimately allows for better resolution, differentiation, and characterization of soft-tissue lesions of the head. Involvement of bone within and around the nasal cavity is also a particularly important diagnostic and prognostic feature of nasal disease and is best evaluated using CT, although MRI has also been shown to offer comparable information in this regard.1
A diagnosis of neoplasia should not be excluded in young dogs with progressive nasal disease. Advanced imaging is recommended to look for characteristic changes which can aid in a diagnosis and guide treatment decisions.
References
- 1.↑
Drees R, Forrest LJ, Chappell R. Comparison of computed tomography and magnetic resonance imaging for the evaluation of canine intranasal neoplasia. J Small Anim Pract. 2009;50(7):334–340. doi:10.1111/j.1748-5827.2009.00729.x
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Thierry F, Longo M, Pecceu E, Zani DD, Schwarz T. Computed tomographic appearance of canine tonsillar neoplasia: 14 cases. Vet Radiol Ultrasound. 2018;59(1):54–63. doi:10.1111/vru.12561
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Lefebvre J, Kuehn NF, Wortinger A. Computed tomography as an aid in the diagnosis of chronic nasal disease in dogs. J Small Anim Pract. 2005;46(6):280–285. doi:10.1111/j.1748-5827.2005.tb00321.x
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Lana SE, Turek MM. Tumors of the respiratory system. In: Vail DM, Thamm DH, Liptak J, eds. Withrow and MacEwen’s Small Animal Clinical Oncology. 6th ed. Saunders; 2019:494–496.
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Russo M, Lamb CR, Jakovljevic S. Distinguishing rhinitis and nasal neoplasia by radiography. Vet Radiol Ultrasound. 2000;41(2):118–124.doi:10.1111/j.1740-8261.2000.tb01464.x
