Oral neoplasia

From Felipedia

Introduction

Unfortunately, the vast majority of feline neoplasms found in the mouths of cats are malignant and carry a poor prognosis. Over 20 different types of cancer have been reported to occur in the oral cavity of felines, although only a few are observed commonly[1]. Among the more common feline oral neoplasms are squamous cell carcinoma (SCC), fibrosarcoma, lymphoma, and malignant melanoma. In fact, SCC alone accounts for about 70% of all feline oral tumors. It is of extreme importance to identify the tumor type and commence treatment early in the course of disease if a favorable treatment outcome is to be achieved. In the majority of cases, however, a clinical cure is not possible. Some oral tumors in cats are obvious, while others may present more subtly. Neoplasia must be suspected in all lesions of the feline oral cavity where an obvious cause is not clear. The first step towards treatment of feline oral neoplasia is establishing a correct diagnosis based on a biopsy.

Any swelling (soft tissue or bony) or abnormal appearance of tissue in the oral cavity must be considered suspicious for neoplasia. In one study, however, it was shown that one-half of the swellings in the lower jaw bone of cats were non-neoplastic. A common, but very subtle presentation of oral neoplasia is when a tooth is able to be extracted too easily. Whenever a tooth can be extracted with less-than-expected difficulty, the area surrounding the alveolus should be biopsied. Common presenting signs for cats with oral neoplasia include: an obvious oral mass, excessive salivation, weight loss, halitosis, bloody oral discharge, and dysphagia.

Obtaining a biopsy of a suspicious lesion in the oral cavity of the cat should be performed under general anesthesia maintained with a cuffed endotracheal tube. Prior to the anesthetic procedure, these cats should have undergone a workup minimally consisting of a physical examination, complete blood count (CBC), blood chemistry panel, urinalysis, and other ancillary procedures as indicated. If neoplasia is suspected prior to the procedure, a radiographic study (3-view chest radiographs) of the thoracic cavity to detect metastatic disease is also warranted.

With the cat under general anesthesia, the oral cavity should be thoroughly examined and all dental pathology recorded. At the time of biopsy, existing dental pathology should be addressed if possible. The area suspected of containing the neoplasm should be radiographed, ideally with intra-oral dental radiographs because of their superior detail.

Diagnosis

The preferred method of obtaining a biopsy sample for oral lesions is an incisional biopsy. An incisional biopsy is harvested from the interior of the lesion, leaving the suspected borders of the tumor behind. Make sure to procure a large enough sample to give the pathologist something to work with. In larger tumors, it is best to obtain multiple samples from different locations within the mass. Try not to take only the center of larger neoplasms, as this area may represent only a center of necrosis. It is also important to note that many tumors will have an overlying covering of hyperplastic epithelium. It is therefore important to make your biopsy deep enough to penetrate through this epithelial covering. Use a biopsy punch, scalpel blade or other sharp cutting device rather then electrocautery or laser, as the latter methods of excision tend to disturb cellular morphology. Once the biopsy sample is removed, the use of cautery or laser for hemostasis is not a problem.

If the biopsy results differ from your clinical impression, question the result. The pathologist will benefit from coupling your description of the tumor’s gross morphology and signalment/history with their histologic findings. It is not uncommon for oral pathologists to change opinions on the nature of oral tumors - this is best done during the planning phase prior to extensive surgery.

Types of oral neoplasia

• Oral squamous-cell carcinoma
• Oral fibrosarcoma
• Miscellaneous

- Oral lymphoma

- Oral osteosarcoma

- Oral melanoma

- Oral chondrosarcoma

- Oral granular cell tumors

- Oral fibropapilloma

- Oral hemangiosarcoma

- Oral ameloblastomas and fibromatous

- Oral ossifying epulides^[2].

While other tumors such as inductive fibro-ameloblastoma ("feline inductive odontogenic tumor") and calcifying epithelial odontogenic tumor ("amyloid-producing odontogenic tumor") have been reported, this has become an area of controversy as other reports suggest both of these tumors should be simply classified as ameloblastomas. The prognosis for cats with oral lymphoma or hemangiosarcoma is presently unknown because it is such a rare site of involvement, however, the use of local therapy (surgery and/or radiation therapy) and adjuvant chemotherapy would be recommended due to its aggressive local and systemic phenotype. The other tumors listed above would be generally thought of as locally aggressive, but minimally to non-metastatic tumors, suggesting that aggressive local therapy would have a high chance of being curative.