Veterinary Society of
Surgical Oncology

GENERAL CONSIDERATIONS

Etiology

  • tumors of nasal cavity represent approximately 1% of all tumors in dogs and less common in cats
  • etiologic factors include exposure to smoke, indoor kerosene or coal combustion and flea spray
  • sex predisposition in cats: male with a male-to-female ratio of 2:1
  • median age: 10 years although cats with non-epithelial tumors may present at an earlier age

Pathophysiology

  • nasal tumors are malignant in 91% cats
  • 43% of nasal tumors in cats are epithelial (50% ADC and 50% SCC) and 28% LSA (71% B-cell, 17% epitheliotropic T cell, and 12% non-epitheliotropic T cell)
  • 25%-40% of malignant tumors are sarcomas such as FSA, CSA, OSA, undifferentiated sarcoma, rhabdomyosarcoma, HSA, leiomyosarcoma, myxosarcoma, and malignant fibrous histiocytoma
  • nasal LSA is rare in both species, but more common in cats and not associated with FeLV infection
  • other round cell tumors include plasmacytoma, transmissible venereal tumor, MCT, and histiocytoma
  • other nasal tumors include malignant melanoma and paranasal meningioma
  • nasal tumors, regardless of histologic type, are characterized by locally invasive growth
  • metastatic rate is low at diagnosis but reported in up to 50% of dogs at necropsy
  • metastatic sites include lymph nodes and lungs ± bone reported in 2 dogs
  • benign nasal tumors include adenoma (19% of epithelial tumors in cats), basal cell tumor, fibroma, and neurofibroma
  • nasal vestibule is the most common site for feline nasal SCC, malignant melanoma, and basal cell tumor

DIAGNOSIS

General Considerations

  • history, clinical signs, survey radiographs, CT, and tissue biopsy
  • hematology and clotting profile to exclude bleeding disorders: platelet count, PCV, ACT, PT, and APTT
  • lymph node aspirates are positive in 10% and thoracic radiographs are usually normal at presentation
  • CSF should be collected if CNS involvement: increased CSF pressure, protein, and rarely cell count are abnormal

Clinical Signs

  • intermittent and progressive unilateral epistaxis ± mucopurulent discharge
  • epistaxis more common with epithelial tumors in cats
  • other clinical signs: sneezing, reverse sneezing, stertorous respiration, dyspnea, facial deformity, epiphora, and neurologic signs (i.e., seizures, behavioural changes, and obtundation) due to direct invasion of cranial vault
  • seizures more common in cats with olfactory neuroblastoma due to extension into the brain
  • mean duration of clinical signs prior to presentation is 3 months
  • DDx: bleeding diathesis, hypertension, bacterial or fungal rhinitis, and developmental anomalies

Imaging

Survey Radiographs

  • nasal radiographs determine extent of disease, presumptive diagnosis, and locate an area for biopsy
  • views: lateral, dorsoventral, frontal sinus, open mouth oblique, and open mouth ventrodorsal
  • radiographic pattern depends on histologic type, duration, and previous treatment
  • mixed pattern of conchal destruction ± increased soft tissue opacity
  • opacification of the ipsilateral frontal sinus is often due to impaired sinus drainage, but extension of the neoplastic process into the frontal sinus can also occur
  • less defined and more destructive appearance with aggressive nasal tumors
  • early neoplasia is difficult to differentiate from rhinitis
  • unilateral increase in nasal opacity with attenuation or obliteration of normal conchal pattern is characteristic of early epithelial nasal neoplasia
  • radiographic appearance becomes more heterogenous due to progressive conchal destruction with tumor progression and growth
  • nasal septum can be deviated or destroyed by neoplastic process, but this is difficult to assess
  • peripheral signs of nasal neoplasia includes soft tissue swelling, facial bone destruction, and periosteal new bone formation, and these signs are usually associated with highly aggressive neoplasms

Computed Tomography

  • CT is preferred for determination of extent of disease and planning for radiation therapy
  • useful for determining extent of disease and involvement of cribriform plate and orbit

Biopsy

  • trans-nostril technique preferred for core biopsy although rhinoscopic and open techniques also used
  • techniques: punch biopsy, large-bore plastic cannula, curette, or grasping (i.e., melon ball) forceps
  • measure from the external nares to the medial canthus to prevent penetration of cribriform plate
  • mild resistance is usually discernible when tumor tissue is encountered
  • other techniques: nasal wash with fluid retrieval for cytologic examination (usually unrewarding), brush cytology (often non-diagnostic for mesenchymal tumors), and rhinoscopic biopsy (although samples are small and superficial)
  • complications: mild to moderate hemorrhage
  • hemorrhage is usually self-limiting but carotid ligation is occasionally required

Clinical Staging

WHO Staging System

Modified Staging System

TREATMENT

Surgery

  • palliative
  • nasal neoplasia is usually advanced with bone invasion and critical location adjacent to eyes and brain
  • acute and chronic morbidity with dorsal rhinotomy
  • no improvement in survival time with surgery compared to conservative management or surgery and radiation therapy compared to radiation therapy alone
  • principal indication for surgery is rostral nasal tumors (i.e., nasal planum and vestibule)
  • unilateral or bilateral carotid artery ligation may be required to control epistaxis

Photodynamic Therapy

  • photodynamic therapy has been used to treated 1 cat and 3 dogs with nasal tumors using pyropheophorbide-a-hexyl ether as the photosensitizing agent
  • photodynamic therapy is well tolerated with no cutaneous sensitization, but facial swelling is common and resolves within 72 hours
  • clinical signs are controlled for 2 weeks to > 54 weeks

External Beam Radiation Therapy

General Considerations

  • CT is preferred for planning of radiation field and dosing to limit exposure of normal tissue
  • role of surgical debulking prior to radiation therapy is unknown
  • surgical debulking is required for orthovoltage but optional for cobalt and megavoltage radiation therapy
  • dose: 18 fractions at 3 Gy per fraction for 54 Gy total dose
  • accelerated dose: 10 fractions at 4.2 Gy per fraction for 42 Gy total dose

Complications

  • oral mucositis, rhinitis, and radiation-induced moist desquamation for 4-8 weeks
  • treatment of oral mucositis includes tannic acid, glutamine (1.3 g/m 2 q 8 hrs PO), and benzydamine
  • ocular changes (i.e., KCS, corneal ulcers, and cataracts) if eyes included in radiation field and dose > 40 Gy

Brachytherapy

  • intracavitary therapy using radioactive isotopes
  • potential problems include dose distribution and radiation exposure to personnel

PROGNOSIS

Nasal Lymphosarcoma

  • MST 1,397 days for cats with nasal LSA treated with radiation therapy alone
  • MST 151 days for cats with nasal LSA treated with chemotherapy alone
  • MST 337 days for cats with nasal LSA treated with radiation therapy and chemotherapy, with a 12-month survival rate 46%

Other Nasal Tumors

  • mean survival time 382 days to 19 months for cats with non-LSA nasal tumors treated with radiation therapy alone, with 1-year survival rate 44%-63% and 2-year survival rate 17%

NASAL CAVITY TUMORS

Stage

Description

I

Ipsilateral tumor with no or minimal bone destruction

II

Bilateral tumor with moderate bone destruction

III

Bilateral tumor with extranasal extension

Stage

Description

I

Unilateral or bilateral tumor confined to nasal passages without frontal sinus involvement

II

Bilateral tumor extending into frontal sinuses with erosion of any bone of the nasal passage

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