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714 Oral Tumors, Malignant

Oral Tumors, Malignant Bonus Material Client Education
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PHYSICAL EXAM FINDINGS
BASIC INFORMATION
radiation therapy.
Halitosis, oral bleeding, facial/oral swelling, before deciding on radical surgery and/or
Definition enlarged mandibular lymph nodes; additional
Neoplastic oral disease is locally invasive and specific findings may vary with tumor type: Differential Diagnosis
can metastasize to distant sites. Oral tumors • Malignant melanoma is pigmented (mela- As for benign oral tumors (p. 711)
comprise approximately 6% of all tumors in notic) or nonpigmented (amelanotic) and
dogs and 10% of all tumors in cats. often lobulated, ulcerative, and friable; Initial Database
necrosis may occur when the tumor out- CBC, serum biochemistry profile, urinalysis,
Synonyms grows its blood supply. A benign variant and thoracic radiographs: to assess for concur-
Malignant oral neoplasia, oral cancer of melanoma may occur in the oral cavity rent illnesses, metastasis
(melanocytoma), which is usually less than
Epidemiology 1 cm in diameter and well circumscribed. Advanced or Confirmatory Testing
SPECIES, AGE, SEX • Fibrosarcoma is often smooth and firm and • Anesthetized oral exam (p. 1140)
• Malignant oral tumors can occur at any may cause generalized disfigurement but • Dental radiography
age, but middle-aged and geriatric pets are rarely bleeds spontaneously. • CT: particularly helpful for maxillary and
overrepresented. • Peripheral nerve sheath tumor tends to grow caudal mandibular masses
• Canine papillary squamous cell carcinoma along larger nerves (e.g., infraorbital nerve • Cytologic exam of oral masses (fine-needle
(SCC) occurs most commonly in adolescent into infraorbital canal and inferior alveolar aspiration, woodpecker technique, or scrap-
and young adult dogs. nerve into mandibular canal). ing from tumor cut surface)
• The most common canine malignant oral • SCC is pink, friable, often verrucous • Cytologic exam of aspirated lymph nodes
tumor is malignant melanoma (melanosar- (cauliflower-like), and may be proliferative or or histopathologic exam of resected lymph
coma [p. 644]), seen most often in dogs > ulcerative. Desmoplasia (formation of fibrous nodes
10 years of age. tissue) secondary to SCC development may • Histopathologic evaluation of incisional or
• The most common feline malignant oral result in a firm tumor on palpation. excisional biopsy
tumor is SCC (p. 939), representing 70% • Osteosarcoma can manifest as a diffuse swell-
of oral tumors in cats. Average age of onset ing of the maxilla or mandible but often also TREATMENT
is 10 years, but cats as young as 5 months exhibits a fleshy, pink or red proliferative
have been affected. component that bleeds readily. Treatment Overview
• Multilobular tumor of bone is locally invasive • Debulking of aggressive oral tumors is rarely
GENETICS, BREED PREDISPOSITION but slow to metastasize and usually located helpful. After a diagnosis is obtained, the
Breeds with pigmented oral mucosa may be at the mandibular ramus, caudal maxilla, mass and a margin of normal surrounding
predisposed to malignant melanoma. zygomatic arch, or calvarium. tissue should be removed comprehensively
• Adenocarcinoma is an invasive, malignant to prevent local recurrence.
RISK FACTORS epithelial neoplasm derived from glandular • If complete removal is not an option, radia-
Factors that increase the risk of feline SCC tissue of the oral cavity, nasal cavity, or tion therapy or chemotherapy may decrease
threefold to fivefold: salivary tissue (major or accessory). the rate of growth, depending on tumor
• Exposure to flea collars • Hemangiosarcoma is a malignant neoplasm type.
• High intake of canned cat food of vascular endothelial origin character-
• Regular ingestion of canned tuna ized by extensive metastasis. It has been Acute General Treatment
reported in the gingiva, tongue, and hard • Removal of a circumscribed mass to the
CONTAGION AND ZOONOSIS palate. normal level of the surrounding gingiva
Canine transmissible venereal tumor (p. 993) • Maxillary, retro-orbital, and caudal pharyn- often serves as an adequate biopsy but may
can manifest as a primary or metastatic tumor geal masses: decreased ability to retropulse not prevent local recurrence. Incisional
on the lips, buccal mucosa, and palatine tonsils. the eye globes and decreased range of mouth biopsies of large masses are warranted to
opening if tumor involves the caudal maxilla, provide information before performing a
Clinical Presentation zygomatic arch, mandibular coronoid radical maxillectomy or mandibulectomy.
DISEASE FORMS/SUBTYPES process, or temporomandibular joint. • Aspiration and/or removal of head and
• Dogs: malignant melanoma, SCC, fibrosar- neck lymph nodes is warranted for staging
coma, osteosarcoma, multilobular tumor of Etiology and Pathophysiology of animals with malignant oral tumors.
bone (multilobular osteochondrosarcoma), Cause is unknown, but a genetic predisposition
mast cell tumor, hemangiosarcoma, peripheral may play a role. Chronic Treatment
nerve sheath tumor, lymphoma (epithelio- • Depending on biopsy results and tumor
tropic lymphoma), adenocarcinoma DIAGNOSIS extent, radical surgery and/or radiation
• Cats: SCC, fibrosarcoma, osteosarcoma, therapy may be treatment options. Even
hemangiosarcoma, malignant melanoma Diagnostic Overview when surgery is an option, consult with
(rare) Diagnosis of malignant oral masses usually a medical oncologist and/or radiation
requires histopathologic analysis of a biopsy, oncologist regarding the need for adjuvant
HISTORY, CHIEF COMPLAINT because many oral masses do not exfoliate or postoperative treatment. Chemotherapy
• Swelling of mandible or maxilla well on fine-needle aspiration, or vascularity may be used as an adjunctive therapy but
• Oral bleeding, halitosis results in hemodilution. Incisional (rather is rarely effective by itself against most oral
• Dysphagia if the mass is large enough to than excisional) biopsy is the preferred initial tumors. Immunotherapy of certain tumors
affect masticatory function and deglutition step for suspected malignancies to provide the shows promise, and a commercial melanoma
• Appetite and activity level often unaffected clinician and client with further information vaccine is available (p. 644).

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