DIAGNOSIS
A thorough history and complete physical examination are the first step in assessing patients that may have nasal cancer.
The history should include questions regarding the duration and progression of the clinical signs. A minimum database including
a complete blood count, serum chemistry profile, and urinalysis is recommended to detect concurrent diseases. Systemic hypertension
should be ruled out as a cause of epistaxis. A coagulation profile including prothrombin time, activated partial thromboplastin
time, and bleeding time or activated clotting time is also recommended to rule out any coagulopathies before invasive diagnostic
procedures.
Once a nasal mass is suspected or has been identified, regional lymph node aspiration, three-view thoracic radiography, imaging
of the nasal cavity, and mass biopsy (rhinoscopy-assisted or blind) should be considered to make a definitive diagnosis. Although
conventional radiography may prove to be beneficial, especially with open-mouth views for identifying space-occupying lesions
within the nasal or frontal sinuses, computed tomography (CT) or magnetic resonance imaging (MRI) of the nasal cavities better
assesses the extent of pathology before biopsy, surgery, or radiation therapy.25,28
Skull radiography
Skull radiography may be used as an initial diagnostic test to evaluate for bone lysis or soft tissue opacities within the
nasal cavities, which may be suggestive of neoplasia. However, given the anatomic complexity of the canine and feline nasal
cavities and the overlapping bony structures, definitive interpretation of routine radiographs may be diagnostically challenging
as well as insensitive for assessing the extent of pathology. In a retrospective study of 42 dogs presenting for nasal disease,
only 10% of the inflammatory rhinitis cases and 64% of the neoplastic cases were accurately diagnosed using conventional radiography
alone.18 The lack of sensitivity and specificity associated with routine radiography, in conjunction with medical imaging advancements,
has increased the use of advanced imaging modalities for documenting nasal cavity pathologies.
Advanced imaging
In general, CT provides superior imaging and visualization of bone, while MRI has greater resolution of soft tissue structures.29,30 Although CT or MRI may theoretically be better suited for identifying disease in specific clinical scenarios, in one small
study of eight dogs with nasal tumors, no difference was seen between CT and MRI for the detection of intracalvarial changes,
suggesting that either modality is appropriate for the identification of nasal tumors.29
However, given the fact that most nasal tumors involve bony structures including nasal turbinates and sinuses, CT is more
commonly used to assess the extent of nasal disease as well as to differentiate between neoplastic and nonneoplastic diseases.
Figure 2. Computed tomography provides high-detail images of a tumor-infiltrated nasal cavity. Note the soft tissue mass
growing within the nasal passage with concurrent osteolytic destruction and the extension of soft tissue growth dorsal to
the nasal cavity.
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With CT, nasal tumors are typically characterized by extensive unilateral turbinate destruction and are often accompanied
by erosive pathology involving contralateral turbinates, nasal septum, frontal sinuses, and the cribriform plate (Figure 2).25,28 In addition to identifying osteolytic abnormalities, CT imaging can also delineate soft tissue disease extension, such as
involvement of the nasopharynx and periorbital regions.25
Finally, CT is integral for defining tumor margins, which is necessary before instituting curative-intent radiation therapy
or en bloc surgical resection.
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