NASAL PLANUM TUMORS

BACKGROUND

Squamous cell carcinoma (SCC) is the most common tumor of the nasal planum in cats, but this tumor is rare in dogs. SCC of the nasal planum and ear pinnae is caused by ultraviolet radiation and is more common in white-haired cats. They are locally invasive tumors. The lesions on the nasal planum progress from initial crusty and reddened lesions to superficial erosion and ulceration (common) and finally to deeply erosive and ulcerated lesions. SCC involves multiple sites in 30% of cats, especially the ear pinnae and eyelids. Nasal planum, pinnae and eyelid SCC in cats rarely metastasizes to the lymph nodes or other organs.


DIAGNOSIS

Nasal planum SCC in cats is highly suspected based on poorly pigmented hair coat, outdoor lifestyle, and the appearance of the nasal planum. An incisional biopsy can be performed, but is often not required.


CLINICAL STAGING

CT or MRI scans of the nose is recommended in dogs, but not cats, to determine the extent of the tumor and plan the surgical excision. Chest radiographs are done to check for metastasis to the lungs. Palpation and possibly aspiration of the regional lymph nodes should be performed to check for nodal metastasis.


TREATMENT

Surgical excision is the recommended treatment for cats and dogs with nasal planum SCC. The cosmetic results are acceptable in cats, but can be challenging in dogs depending on the extent of resection. Cats are initially reluctant to eat because they rely on their sense of smell to stimulate their appetite. However, this is temporary and feeding tubes are rarely required.


Cryosurgery is an option for cats with small, superficial lesions. However, multiple treatments are often required and 20% of nasal planum tumors do not respond after 2-3 treatments.


Localized (strontium) or external beam radiation therapy, intralesional chemotherapy, and photodynamic therapy have also been reported for the treatment of nasal planum SCC in cats.


PROGNOSIS

The prognosis for cats with nasal planum SCC is very good following treatment with surgery, cryosurgery, or radiation therapy. Local recurrence rates are less than 20% with a median disease-free interval of 594 days for surgery alone and 426 days for cats with SCC in multiple locations. The median survival time following surgical excision is 673 days for cats with nasal planum lesions and 530 days for cats with SCC in multiple locations.

The typical superficial erosive and ulcerated appearance of a SCC of the nasal planum in a cat.

The typical appearance of a cat following resection of the nasal planum and pinnae for SCC in multiple locations. Photo courtesy of Dr. Maurine Thomson.

Cosmetic appearance immediately after resection of the nasal planum in a cat.