A survey of epithelial odontogenic tumors and cysts in dogs and cats.

A retrospective histologic study of 12 canine and eight feline epithelial odontogenic tumors and cysts was conducted from oral masses (n = 3,917) obtained between 1980 and 1990. No sex or breed predilection was identified. Ameloblastoma was observed in two dogs (case Nos. 1, 2) 6 and 8 months of age. Calcifying epithelial odontogenic tumors were seen in a dog (case No. 3) and in two cats (case Nos. 4, 5) between 8 and 16 years of age. Ameloblastic fibroma (or fibroameloblastoma) was observed in cats (case Nos. 6-10) only. Inductive fibroameloblastoma was observed in four cats (case Nos. 6-9) up to 1 year of age, whereas ameloblastic fibroma was seen in a 14-year-old cat (case No. 10). A single ameloblastic odontoma was identified in a 20-month-old dog (case No. 11). Two complex odontomas occurred in a 6-month-old (case No. 12) and a 4-year-old (case No. 13) dog. Odontogenic cysts were identified in five dogs (case Nos. 14-18) aged 4.5 months to 16 years and in a 1-year-old cat (case No. 19) and have not been previously reported in these species. These cysts were lined by a stratified epithelium reminiscent of the appearance of ameloblastic epithelium. An odontogenic keratocyst with prominent central parakeratotic keratinization was identified in one 9-year-old female dog (case No. 20). Almost all epithelial odontogenic tumors were circumscribed, benign tumors that warranted a good prognosis for survival, although local recurrence may have followed (or may follow) incomplete excision. Calcifying epithelial odontogenic tumors may be locally invasive. Of six odontogenic cysts (case Nos. 14-19), two (case Nos. 15, 18) gave rise to basi-squamous carcinomas. The classification and behavior of epithelial odontogenic tumors and cysts in human beings, dogs, and cats are discussed.