CT features of malignant and benign oral tumors in 28 dogs

Abstract

An improved understanding of the computed tomographic (CT) features for malignant versus benign oral tumors would be helpful for guiding prognosis and treatment planning decisions in dogs. This retrospective, multi-center, observational study compared the CT features of malignant and benign tumors in 28 dogs with 31 oral masses. Malignant tumors were present in 20 dogs, including malignant melanoma (n = 14), squamous cell carcinoma (SCC, n = 4), adenocarcinoma (n = 1), and fibrosarcoma (n = 1).Eight dogs had benign tumors, including giant cell granuloma (n = 2), peripheral odontogenic fibroma (n = 2), acanthomatous ameloblastoma (n = 2), plasmacytoma (n = 1), and oncocytoma (n = 1). Common CT features of malignant tumors included heterogeneous enhancement, tumor invasion into the adjacent bone, tooth loss, and ipsilateral mandibular lymphadenopathy. Malignant tumors were significantly larger than benign tumors. Bone lysis was found in benign tumors (n = 4) such as acanthomatous ameloblastoma, giant cell granuloma, and plasmacytoma. The bone lysis was a welldefined geographic area regardless of malignancy and tumor type. In periosteal reactions, amorphous patterns were seen in both malignant (n = 2) and benign tumors (n = 2); the latter subgroup also showed solid patterns. Bone expansion (n = 2) was identified in malignant melanoma and acanthomatous ameloblastoma. Findings supported a diagnosis of possible malignancy for dogs with oral tumors having the following CT characteristics: large size, heterogeneous contrast enhancement pattern, bone lysis, tooth loss, and ipsilateral lymphadenopathy. However, there was a considerable overlap of CT findings among the different types of oral tumors and between benign and malignant tumors. Histological evaluation therefore remains necessary for definitive diagnosis.

Computed Tomographic and Magnetic Resonance Imaging Features of Oral Melanoma in a Dog

“…There are several reports on the identifying features of oral tumors on CT scans in veterinary medicine, with melanoma accounting for many cases. Malignant oral tumors, including oral melanoma, exhibit several noteworthy features on CT, such as their substantial size, a heterogeneous contrast enhancement pattern, bone lysis, tooth loss, and displacement, invasion of the nasal or oral cavity, and the presence of ipsilateral lymphadenopathy (2,9). All these distinct CT imaging features of malignant oral tumors were manifested in the current case.…”

“…Previous studies have reported the features of oral melanoma on computed tomography (CT). These include large size, bone invasions such as osteolysis, a heterogenous contrast enhancement pattern, and ipsilateral lymphadenopathy (2,9). There are few reports have described the findings of magnetic resonance imaging (MRI) of oral melanoma in dogs.…”

Dynamic contrast-enhanced computed tomography in 11 dogs with orofacial tumors

“…The most common malignant types are malignant melanoma, squamous cell carcinoma, and sarcoma (fibrosarcoma, less frequently osteosarcoma), whereas the most common benign oral tumors are odontogenic tumors, especially acanthomatous ameloblastoma. [1][2][3] The treatment of choice for maxillary and mandibular tumors is excisional surgery, alone or with adjuvant radiotherapy (RT) and chemotherapy or other medical therapy depending on the type of tumor. [4][5][6][7][8][9][10][11] However, facial surgery is associated with significant morbidity and esthetic consequences that might discourage owners, 2 and RT alone (or in association with chemotherapy) is sometimes preferred.…”