Page 525 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

CHAPTER 24 Tumors of the Respiratory System 503

nasal signs controlled for 10 months after definitive RT for polyp The majority of cases were B-cell (68%) and 20% were T-cell, with
recurrence. The role of RT in the management of nasal polyps is 12% having a mixed population of B- and T-cells. 186 In another
In
189
not clear.
study of 39 cases, 28% were small cell and 87% were B cell.
VetBooks.ir assessment of treatment efficacy in canine sinonasal cancer is this study they also evaluated FeLV viral antigens (p27 and gp70)
A major pitfall of many veterinary studies with respect to
by immunohistochemistry (IHC) and found that 54% of samples
the need for advanced imaging to assess tumor response. Tumor were positive, although cases were not serologically tested. The
response and TTP are the most representative measures of treat- majority of cases in this series did not receive therapy, so the effect
ment efficacy. Regular diagnostic imaging, ideally CT or MRI, is of viral positivity on outcome is unknown. Because lymphoma
necessary for accurate determination of these endpoints. Due to makes up a high percentage of feline nasal tumor cases, special
high costs and the need for anesthesia, follow-up is rarely done stains may be helpful in obtaining a correct diagnosis. In a retro-
in this manner. Analyzing the return of clinical signs as an indi- spective study of 232 feline nasal tumor biopsies reviewed by two
cation of tumor recurrence is problematic because similar signs pathologists, disagreement in diagnosis was seen in 15 cases, 14 of
can result from rhinitis secondary to therapy (RT and/or surgery) which were originally diagnosed as carcinoma. 190 IHC with epi-
or residual tumor. 178 Assessment of survival time may be biased thelial and lymphoid markers showed that the original diagnosis
by the use of additional treatments on suspicion of progressive was incorrect 67% of the time, indicating the usefulness of IHC in
disease and by the decision for euthanasia, which can vary greatly establishing a correct diagnosis in feline nasal tumors.
from one pet owner to another. Furthermore, inconsistencies in Radiographs of the nasal cavity have been reported as a diag-
methodology between studies and even within individual reports, nostic tool in cats with both chronic rhinitis and nasal neoplasia.
as well as a lack of controlled studies, have limited the informed Although no radiographic sign is entirely specific for neoplasia,
development of the optimal treatment approach for sinonasal findings with the highest predictive value for cancer include dis-
tumors in dogs. placement of midline structures, unilateral changes such as soft
tissue opacity and loss of turbinate detail, and evidence of bone
Feline Sinonasal Tumors invasion. 191 Similarly, as CT scan becomes a common imaging
tool, reports of the characteristic findings of scans from cats with
Nasal and sinus cavity tumors in the cat are malignant in more sinonasal disease of all etiologies have been published. 192–194 One
than 90% of the histologically diagnosed cases. They occur in an retrospective assessment of CT imaging in 62 cats with sinonasal
older population of cats with a mean age reported between 9 and disease showed that, although certain findings such as osteolysis
10 years. 179–181 In general, these tumors are locally invasive and of paranasal bones, extension of disease into the orbit of facial
associated with a low metastatic rate at the time of diagnosis. 180,182 soft tissues, the presence of a space-occupying mass, and turbinate
Clinical signs related to sinonasal tumors in cats overlap with destruction may suggest a CT diagnosis of neoplasia over rhinitis,
those of other causes of chronic nasal disease. 179,181 These include nasal biopsy is necessary for confirmation. 192 Another study evalu-
nasal discharge, upper respiratory tract dyspnea, sneezing, epi- ated the clinical characteristics and CT findings in 43 cats and
staxis, facial swelling, ocular discharge, and weight loss. 179–181,183– found that those with neoplasia were significantly more likely to
185 Although each of these signs can occur with both neoplasia and have unilateral lysis of the ethmoturbinates as well as dorsal and
rhinitis, in some reports, certain signs are more commonly asso- lateral maxilla, lysis of the vomer bone and ventral maxilla, and
ciated with neoplasia such as unilateral discharge or epistaxis, 179 unilateral soft tissue or fluid in the sphenoid recess, frontal sinus,
whereas in others, the character of the clinical signs does not dis- or retrobulbar space. Interestingly, in that study population, crib-
tinguish the underlying cause. 181 The median duration of clinical riform plate lysis was not significantly associated with neoplasia. 193
signs before diagnosis is several months, and many cats will experi- In another report describing CT findings in cats with confirmed
ence temporary alleviation of clinical signs with use of antibiotics fungal rhinitis, they found that some of the features overlap with
and or corticosteroids. 179–181 Differential diagnoses for chronic those seen in neoplasia patients, including older age at the time of
nasal signs include chronic rhinitis, infectious rhinitis, foreign diagnosis, soft tissue mass, and osteolysis. Another study sought
body, nasal polyp, nasopharyngeal stenosis, and trauma. to determine whether CT characteristics of nasal passages and
Lymphoma is the most commonly diagnosed tumor type in medial retropharyngeal LNs (MRPLNs) could be used to distin-
the feline nasal cavity and sinuses, followed by epithelial neo- guish neoplasia from rhinitis. 195 Thirty-four cats with rhinitis and
plasms (carcinoma, adenocarcinoma, SCC). Less frequently 22 cats with neoplasia were evaluated. These authors found that in
reported tumor types include sarcomas (fibrosarcoma, osteosar- addition to nasal passage findings typically sited in other studies,
coma, chondrosarcoma), MCT, melanoma, plasmacytoma, olfac- the MRPLN characteristics that were significantly associated with
tory neuroblastoma, and benign lesions such as nasal hamartoma, neoplasia included abnormal MRPLN hilus, height asymmetry,
chondroma, and neurofibroma. 179–181,186,187 and decreased MRPLN precontrast heterogeneity. Although these
Diagnostic principles are similar to those in the dog. A tissue studies confirm the utility of CT scan determining extent of dis-
sample is required to make a definitive diagnosis of cancer in most ease, no one group of features replaces histopathology for defini-
cases. DeLorenzi et al evaluated cytology from squash prepara- tive diagnosis.
tions obtained from endoscopic biopsies of nasopharyngeal masses Even though the metastatic rate of feline sinonasal cancer at
in cats and found that cytologic results were in good agreement the time of diagnosis is reportedly low, any enlarged regional LNs
with histopathology with an overall accuracy of 90%. 188 However, should be evaluated cytologically to differentiate a reactive process
distinguishing lymphoma from lymphoid inflammatory disease from metastasis. In a recent report of 123 cases of feline sinona-
was not as accurate, and histopathologic confirmation was rec- sal cancer, 21 cats had regional lymphadenopathy. None showed
ommended. 188 Another study evaluated the histopathologic and cytologic evidence of metastasis. 180
cytologic features of nasal lymphoma in 50 cases. Ninety-one per- As in the dog, RT continues to be the predominant local
cent of cases were classified as immunoblastic lymphoma accord- therapy of choice for this disease. Reports of treatment for feline
ing to the National Institutes of Health Working Formulation. nonlymphoma sinonasal tumors are few, and case numbers are