Feline oral neoplasms: a twenty-year retrospective survey and expression of amelogenin and ameloblastin in feline conventional (keratinizing) ameloblastoma and oral squamous cell carcinoma.
Feline oral neoplasms are underrepresented in scientific studies and reviews when compared with similar canine neoplasms. Oral neoplasms include those of the oral cavity, pharynx, gingiva, dental structures (odontogenic neoplasms), tongue, tonsils, and salivary glands. Oral neoplasms are common in cats representing 10-60% of all neoplasms in previous publications. In Chapter 2 of the thesis, 569 surgical biopsies obtained from feline oral cavities submitted for routine diagnostic purposes between January 1998 and December 2019 were reviewed. Twenty-two different neoplasms were found. A majority of neoplasms were malignant (85%). The most frequently diagnosed were: squamous cell carcinoma (68.8%), peripheral odontogenic fibroma (5.3%), fibrosarcoma (4.4%), peripheral giant cell granuloma (3.5%), conventional (keratinizing) ameloblastoma (3.5%), and adenocarcinoma of the salivary gland (2.46%). The current study is the first one of its type conducted in Canada and the second one in North America. Compared to a previous North American study, fewer cases of fibrosarcoma (4.4% vs 12.9 %), and significantly more cases of conventional (keratinizing) ameloblastoma (3.5% vs 0.3%) were reported. Several neoplasms were identified in this study that were not seen in the previous study, these included: plasma cell neoplasm, hemangiosarcoma, and osteoma. Oral squamous cell carcinoma (OSCC) and conventional ameloblastoma (CA) represent two epithelium-derived neoplasms that affect the oral cavity of cats and histologically may look similar. In Chapter 3, two immunohistochemical (IHC) markers, amelogenin and ameloblastin, were compared to determine usefulness in differentiation of the two neoplasms. The expression of amelogenin and ameloblastin has been previously established in the feline tooth bud and canine and human odontogenic tumors. The aim of this study was to characterize the amelogenin and ameloblastin expression profile of OSCC in comparison to CA. Samples from 15 OSCC and 15 CA cases were examined. Amelogenin expression was intranuclear in 15 OSCC cases, with all cases demonstrating high staining intensity. 14 of 15 CA cases demonstrated mild-moderate intranuclear staining intensity. Neither CA nor SCC expressed ameloblastin. Ki67 stained SCC samples had proliferation index 29.80% and CA had proliferation index 16.51%. The difference in staining pattern and intensity of amelogenin and ameloblastin along with proliferation index of Ki76 in OSCC and CA did not help distinguish between the two neoplasia types. The combined conclusions of the investigations are feline oral neoplasms are still an under researched area, ameloblastoma might be more common than previously thought, amelogenin and ameloblastin are not specifically expressed in odontogenic neoplasia, and Ki67 labeling index is not significantly different between OSCC and CA.
Cats, feline, soft tissue, oral neoplasms, odontogenic neoplasms, squamous cell carcinoma, ameloblastoma, amelogenin, ameloblastin, Ki-67.
Master of Science (M.Sc.)