Page 293 - Small Animal Internal Medicine, 6th Edition

CHAPTER 15 Disorders of the Nasal Cavity 265

NASAL TUMORS mucosa and, in some patients, secondary infection. Super-
ficial specimens are more likely to lead to a misdiagnosis.
VetBooks.ir Most nasal tumors in the dog and cat are malignant. Adeno- evaluation of the dog or cat. Imaging, rhinoscopy, and biopsy
Not all cases of neoplasia will be diagnosed on initial
carcinoma, squamous cell carcinoma, and undifferentiated
carcinoma are common nasal tumors in dogs. Lymphoma
persistent signs in which a definitive diagnosis has not been
and adenocarcinoma are common in cats. Fibrosarcomas may need to be repeated in 1 to 3 months in animals with
and other sarcomas also occur in both species. Benign made. CT and MRI are more sensitive techniques than
tumors include adenomas, fibromas, papillomas, and trans- routine radiography for imaging nasal tumors, and one of
missible venereal tumors (the latter only in dogs). these should be performed when available (see Fig. 14.8, B).
Surgical exploration is occasionally necessary to obtain a
Clinical Features definitive diagnosis.
Nasal tumors usually occur in older animals but cannot be Once a definitive diagnosis has been made, determining
excluded from the differential diagnosis of young dogs and the extent of disease can help in assessing the feasibility of
cats. No breed predisposition has been consistently surgical or radiation therapy versus chemotherapy. Some
identified. information can be obtained from high-quality nasal radio-
The clinical features of nasal tumors are usually chronic graphs, but CT and MRI are more sensitive methods for
and reflect the locally invasive nature of these tumors. Nasal evaluating the extent of abnormal tissue. Aspirates of man-
discharge is the most common complaint. The discharge can dibular lymph nodes should be examined cytologically for
be serous, mucoid, mucopurulent, or hemorrhagic. One or evidence of local spread. Thoracic radiographs are evaluated,
both nostrils can be involved. With bilateral involvement, the although pulmonary metastases are uncommon at the time
discharge is often worse from one nostril than from the of initial diagnosis. Cytologic evaluation of bone marrow
other. For many animals, the discharge is initially unilateral aspirates, as well as abdominal radiography or ultrasound, is
and progresses to bilateral. Sneezing may be reported and indicated for patients with lymphoma. Cats with lymphoma
may be the only clinical sign early in the disease process. are also tested for FeLV and FIV.
Obstruction of the nasal cavity by the tumor may cause
decreased or absent air flow through one or both of the Treatment
nares. Benign tumors, though rare, may be treatable with surgical
Deformation of the facial bones, hard palate, or maxillary excision. Radiation therapy is generally recommended for
dental arcade may be visible (see Fig. 13.5). Tumor growth malignant tumors. Chemotherapy is considered for adjunc-
extending into the cranial vault can result in neurologic tive therapy for patients with metastatic disease, or as a sole
signs. Growth into the orbit may cause exophthalmos or treatment for patients with lymphoma (Chapter 79). Chemo-
inability to retropulse the eye. Animals only rarely experi- therapy can also be the sole treatment when radiation is not
ence neurologic signs (e.g., seizures, behavior changes, readily available. Carcinomas may be responsive to cisplatin,
abnormal mental status) or ocular abnormalities as the carboplatin, or multiagent chemotherapy. (See Chapter 76
primary complaints (i.e., no signs of nasal discharge). Weight for a discussion of general principles for the selection of
loss and anorexia are other rare complaints. chemotherapy.) Surgical excision alone is not successful for
managing malignant nasal tumors, although some oncolo-
Diagnosis gists have recommended surgical excision following radia-
A diagnosis of neoplasia is supported by typical abnormali- tion therapy.
ties detected by imaging of the nasal cavity and frontal Palliation of clinical signs can often be achieved with
sinuses or rhinoscopy. Abnormalities can reflect soft tissue radiation treatment at a reduced dose and frequency, avoid-
mass lesions; turbinate, vomer bone, or facial bone destruc- ing many of the side effects of full dose radiation. Similarly,
tion; or diffuse infiltration of the mucosa with neoplastic and palliation can sometimes be achieved with piroxicam
inflammatory cells (see Figs. 14.2, 14.4, and 14.8, B). Identi- (DOSE) or corticosteroids at antiinflammatory dosages
fication of neoplastic cells in fine-needle aspirates of nasal (prednisone or prednisolone, 0.5-1 mg/kg/day orally, gradu-
masses or affected mandibular lymph nodes may further ally tapered to lowest effective dose). Note that these two
support the diagnosis. Be aware that a cytologic diagnosis of drugs should not be given in combination.
neoplasia from a mass aspirate must be accepted cautiously,
with consideration of concurrent inflammation and poten- Prognosis
tially marked hyperplastic and metaplastic change. Further- The prognosis for dogs and cats with malignant nasal tumors
more, in some cases the cytologic characteristics of lymphoma is poor without treatment. Survival after diagnosis is usually
and carcinoma will mimic each other, which may lead to an only a few months. Euthanasia is often requested because
erroneous classification of the neoplasia. of persistent epistaxis or discharge, and eventually, labored
A definitive diagnosis requires histopathologic examina- respirations, anorexia and weight loss, or neurologic signs.
tion of a biopsy specimen. Biopsy specimens should always Epistaxis is a poor prognostic indicator. In a study of 132
include tissue from deep within the lesion. Nasal neoplasms dogs with untreated nasal carcinoma by Rassnick et al.
frequently cause a marked inflammatory response of the nasal (2006), the median survival time of dogs with epistaxis was