Management of a locally aggressive mandibular mass in a dog
Benign and malignant oral masses are commonly encountered in the oral cavities of dogs and cats. Benign oral masses found within the oral cavity do not metastasize, but they are often locally invasive. The behavior of malignant masses are type- and, in some cases, site-dependent. This case describes a patient with such a mass and outlines the importance of early detection and intervention of oral masses in veterinary patients.
Discussion of the options and intent of treatment with this patient's pet owners is essential. They should understand that most oral masses can be successfully resected surgically. A discussion of potential common malignancies and their systemic potential is also indicated. The worst prognosis comes with oral melanoma that is quick to metastasize. Squamous cell carcinoma carries a poor prognosis if tonsillar involvement is present, but curative excision is possible in other oral locations if the mass is detected prior to distant metastasis. Only 20 percent of fibrosarcomas metastasize, and excision plus or minus radiation and chemotherapy are options. Pet owners must understand that masses of this size and extent often require partial jaw removal. If they are unwilling to pursue therapy, biopsy is of no value to the patient.
In this case, the patient was anesthetized, and a deep wedge-shaped biopsy sample of the mass was obtained rostrally, avoiding the traumatized portion. No sutures were placed, and bleeding was minimal. Histopathologic examination revealed acanthomatous ameloblastoma. Formerly classified as acanthomatous epulis, acanthomatous ameloblastoma is a common benign but locally invasive tumor. Surgical resection by a board-certified veterinary dentist or surgeon is the treatment of choice for this condition.
What considerations will be discussed with this client upon referral?
Had this been a malignancy, diagnostic tests to determine metastasis and staging would have predicated excision. In the case of any locally aggressive oral mass, margin determination is ideally determined by computed tomography (CT). In this case, CT was not readily available, and margin estimation was based on gross appearance because of the lack of radiographic changes. In patients with acanthomatous ameloblastoma, a mandibulectomy or maxillectomy with a minimum of 1-cm margins is the treatment of choice for definitive resolution.