ORAL PATHOLOGY DENTISTRY Jeanne R. Perrone, CVT, VTS (Dentistry) This session will deal with the commonly seen neoplasms of the oral cavity and those conditions that look like tumors, but arise from an outside source. Oral tumors arise from the gingiva, buccal mucosa, tongue, mandible, maxilla, palate, dental structures, or tonsils. Neoplasms from Trauma Gum Chewers Syndrome: This syndrome is caused by mechanical trauma. The pet chews on the inside of its cheek or tongue. This causes a proliferative granulomatous hyperplasia to occur at the site. If the chewing is mild, the damage will be low. In extreme cases, the lesions can become large, bleed regularly, and cause pain (Lobprise et al. 2000). Neoplasms from Infectious Agents Gingival Hyperplasia Gingival hyperplasia is a proliferation of the tissue of the attached gingiva. It may occur due to an inflammatory response such as dental plaque or calculus. The excessive gingival tissue can form what’s called a “false pocket”— the extra tissue increases the depth of the sulcus. The hyperplastic tissue is usually benign. Treatment consists of treating the underlying periodontal disease and a gingivectomy to remove the excess tissue. This condition can be an inherited trait in certain breeds such as boxers, Great Danes, collies, Doberman pinschers, and Dalmatians (Tholen et al. 1982). Pyogenic Granuloma These lesions result from irritation of a specific site on the gingiva. The gingiva proliferates the area with granulation tissue. This irritation can be a foreign body or an infected wound. Removing the irritant will usually remove the lesion (Tholen et al. 1982). Feline Eosinophilic Granuloma These are chronic, progressive lesions that involve not only the lips and the oral cavity, but the skin as well. It occurs most often in three-year-old spayed cats. The lesions are large, ulcerated, erythematous, and raised. The causes have been anything from grooming to the idea that it is an immune-mediated disease. A biopsy should be taken to rule out neoplasia or autoimmune disorder. Treatment consists of decreasing doses of steroids, but recurrence is common. Radiation and cryosurgery have yielded the best results (Harvey et al. 1993; Tholen et al. 1982). Chronic Alveolar Osteitis This condition is commonly associated with the maxillary canines and seen most often in the cat. One can see a distinct bulging of the gingiva on the buccal aspect of the canine tooth. It can sometimes involve the region of the mandibular symphysis. In most cases, this arises as a result of chronic inflammation, usually periodontal disease. Periodontal pockets may be present. The periodontal disease should be treated appropriately, but the osseous changes are usually irreversible. If a tooth needs to be extracted, closing the extraction site may be tricky. Making releasing incisions, raising a periodontal flap, and performing alveoloplasty to flatten the bulge will make the closure go more smoothly (Lobprise et al. 2000). Infectious Papilloma This is a viral disease usually seen in young dogs. It is caused by infection with a papovavirus. The lesions are usually white, smooth, and slightly elevated. They are found around the lips and the tongue. The warts may come in singles or multiples and persist for four to eight weeks. The warts undergo spontaneous remission or can be surgically removed in advanced cases (Dhaliwal et al. 1998; Norris et al. 1985). Oropharyngeal Tumors Epulides: Epulis is a clinically descriptive term. The term refers to any localized swelling on the gingiva. They tend to be rare in cats. Epulides contain dental lamina cells from the periodontal ligament or gingival epithelium. These tumors appear most commonly near the canine teeth, but can appear anywhere in the oral cavity (Niemic 2010). Historically, epulides have been divided into three types (Caiafa 2003). Fibromatous Epulis/Peripheral Odontogenic Fibroma This is the most common type. The lesions are usually smooth, pink, and pedunculated. They do not invade bone (Caiafa 2003). Ossifying Epulis/Peripheral Odontogenic Fibroma This originates from the periodontal ligament/gingival epithelium. They are slow-growing and calcified with a broader base of attachment. There are also strands of odontogenic material often present (Caiafa 2003). Acanthomatous Epulis/Acanthomatous Ameloblastoma The acanthomatous epulis shows a biological behavior similar to intraosseous ameloblastoma in humans and recently the term canine acanthomatous ameloblastoma has been recommended. These can be locally aggressive, displace teeth, and invade into bone. When the bone lysis is visible radiographically, a significant amount of the bone cortex has been destroyed. These tumors do not metastasize, so a wide local incision is curative (Norris et al. 1985; Caiafa 2003). Types of Oral Tumors There are two classifications of tumors which are determined by their cell of origin. Nonodontogenic arise from structures of the oral cavity and odontogenic arise from the dental laminar epithelium (Dhaliwal et al. 1998). Oral tumors are generally locally aggressive with metastasis being infrequent. The exception to this is in the case of malignant melanoma, high grade sarcomas, and tonsillar squamous cell carcinoma. Benign oral tumors have an excellent prognosis with treatment (Dhaliwal et al. 1998). Breed and Species Disposition The oral cavity is the fourth most common site of malignant neoplasia in dogs and cats (Harvey et al. 1993). The three most common oral tumors in dogs are malignant melanoma, nontonsillar squamous cell carcinoma, and fibrosarcoma. Oral tumors occur 2.6 times more often in dogs than cats and 2.4 times more often in male dogs than females. Ten percent of all tumors in cats are seen in the oral cavity with 90% of those oral tumors being malignant. The age disposition for tumors of the oral cavity is commonly seen in geriatric patients with the exception of oral fibrosarcoma, which can be seen in young large breed dogs. Common breed disposition for oral tumors is cocker spaniels, poodles, German shepherd dogs, German shorthaired pointers, Weimaraners, golden retrievers, and boxers (Dhaliwal et al. 1998). Clinical Symptoms Patients will present with the following symptoms: dysphagia, halitosis, hemorrhage, ptyalism, anorexia, sneezing, ocular or nasal discharge, pawing at the mouth, facial swelling, tooth displacement, thickening of the bone of the maxilla or mandible, exophthalmos, and pain. In the case of malignant oral tumors, by the onset of clinical symptoms the stage of the tumor can be quite advanced (Dhaliwal et al. 1998). Nonodontogenic Tumors Squamous Cell Carcinoma (SCC) It is the most common oral neoplasia in dogs and cats. It is categorized as either tonsillar or nontonsillar depending on the location in the oral cavity. Tumors are pink in color, firm, and irregular. In cats, they may also have firm white nodules. In nontonsillar SCC, the most common sites of involvement are the lips and tongue and have a tendency to grow rapidly, ulcerate, and become secondarily infected. Nontonsillar SCC is locally invasive, rarely metastasizes, and is radiation sensitive. Tonsillar SCC is more aggressive with metastasis possible to the regional lymph nodes and lungs and is radiation resistant. Prognosis is dependent on the stage and location of the tumor. Cats generally have a poor prognosis for long term survival (Dhaliwal et al. 1998; Norris et al. 1985). Malignant Melanoma (MM) Malignant melanoma is the most common tumor in dogs. They originate from the mucosal or gingival melanocytes. Tumors are generally found on the gingival, labial, or buccal mucosa or the hard palate. They are locally invasive, either variably pigmented or amelanotic, ulcerated and necrotic; thus, halitosis will be present. Fifty percent of patients will have early metastasis. Prognosis is poor if the tumor has metastasized and guarded if it has not. Malignant melanoma is rare in cats (Dhaliwal et al. 1998). Fibrosarcoma (FSA) Fibrosarcomas are the second most common malignant tumor in dogs and cats. They originate from the stroma of the gingiva or the soft palate, with the gingiva being the most common site of involvement. The average age of the patient is eight years old in dogs and 10 years old in cats. The tumors are firm, flat, multilobulated, and deeply attached to underlying tissue. Ulceration is not commonly seen. They respond poorly to radiation and chemotherapy. Recurrence can also occur postsurgical excision. Prognosis is poor (Dhaliwal et al. 1998). Odontogenic Tumors Odontogenic tumors are unique to the jaw bone and teeth. The tumors originate from the tissues associated with tooth development. Knowledge of odontogenesis is helpful to better understand these tumors. The tumors are classified according to their tissue of origin. There are epithelial (ectodermal) odontogenic tumors that arise from the odontogenic epithelium. There is no hard tissue formation so they are also classified as noninductive. Connective tissue (mesodermal) odontogenic tumors arise from connective tissue elements. Mixed odontogenic tumors contain both epithelium and connective tissue. These tumors have hard tissue formation and are further classified as inductive (Dhaliwal et al. 1998; Norris et al. 1985; Caiafa 2003). Ameloblastoma (Epithelial Odontogenic Tumor, Noninductive) This is the most common odontogenic tumor. They are locally invasive, intraosseous tumors with histological similarities to the acanthomatous epulis. They cause osteolysis, so loose teeth are often seen. The tumors