Ameloblastoma and Keratinizing Ameloblastoma in Dogs

Abstract

Abstract. Ameloblastomas reviewed in this report were locally invasive neoplasms arising from the epithelial structures of the dental lamina, and were characterized histologically by features which are unique to dental lamina epithelium. These include the formation of epithelial sheets in which the cells nearest the stroma form a palisading row aligned perpendicularly to the basement membrane and the cells toward the center separate from each other except at desmosomal attachments. This is similar to the appearance of the stellate reticulum of the early enamel organ. Other features include epithelial cords which branch and interconnect, and the intimate association of epithelial structures and collagenous matrix. In our dogs, other important features were the deposition of inclusions similar in appearance to enamel matrix between the cells of the epithelium and various degrees of keratinization. All ameloblastomas studied were locally invasive tumors which occurred at various sites on the gingiva. The average age of the dogs was 8.7 years and the age range was three to 13 years. Radiographically, all of the tumors studied resulted in periodontal osteolysis. Six dogs were treated with radiation therapy, but details of the radiotherapy of two dogs could not be located. Of the other four dogs, one is alive 48 months after radiotherapy with no evidence of tumor regrowth. Regrowth of the oral tumor was apparent in the other three dogs six, 21, and 34 months after completion of the radiotherapy.Three dogs were treated by radical mandibulectomy; all are alive with no evidence of tumor recurrence at two, 20, and 28 months postoperatively. Two dogs had local dissection (curettage) of tumors and the tumors recurred at 12 and 15 months after surgery. One dog was euthanatized after diagnosis of the oral tumor because of a progressive neuropathy.

Ameloblastoma in a wild black rat snake (Pantherophis alleghaniensis)

“…The presence of few but distinct desmosomes on the contact surfaces of the palisading neoplastic cells confirmed the epithelial origination of the neoplastic population and is described in EM evaluations of ameloblastomas. 7,17 Visualization of tonofilaments within the cytoplasm of the neoplastic population is consistent with previous reports of both ameloblastoma as well as squamous cell carcinoma. The microvilli that were seen on the apical borders of the neoplastic cells are also a frequently described characteristic of ameloblastomas.…”

“…3,12 In veterinary species, odontogenic tumors have been documented extensively in dogs and less commonly in cats. 6,7 In nonmammalian species, ameloblastomas have been characterized in captive-reared Chinook salmon (Oncorhynchus tshawytscha). 8 A 1.22 kg, wild, adult black rat snake (Pantherophis alleghaniensis), with a marked oral swelling, was brought to the University of Georgia Veterinary Teaching Hospital, Zoological Medicine Service (Athens, Georgia) subsequent to being found by a good samaritan.…”

Peripheral Acanthomatous Ameloblasoma in a Rabbit with Review of Previous Submissions of the Armed Forces Institute of Pathology Wednesday Slide Conference

“…In animals, ameloblastomas located in the mandibular arcade occur nearly three times more often than in the maxillary arcade [12], whereas in dogs the frequency is about the same for both mandible and maxilla [3]. While the frequency of the peripheral or soft tissue ameloblastomas in animals has not been described, the location of the tumor of the angulus orisa is unusual and makes its developmental origin difficult to explain.…”

Spontaneous Complex Odontoma in a Sprague-Dawley Rat.

“…, Chuel-Kyu KIM 1) , Byeongwoo AHN 1) , Jin Seok KANG 1) , Ki Taek NAM 1) , Dae Joong KIM 2) , Dong Un HAN 3) , Kwonil JUNG 3) , Han-Kook CHUNG 3) , Seung-Kwon HA 3) , Changsun CHOI 3) , Wan-Seob CHO 3) , Junghyun KIM 3) and Chanhee CHAE 3) Odontogenic neoplasms are rare in rats. They are named according to their degree of differentiation.…”

“…Thus, neoplasms composed entirely of epithelium are unable to produce hard tissues. Such neoplasms are termed ameloblastomas [3]. Those neoplasms which contain hard tissues and are mixed with epithelial and mesenchymal origins, are termed odontomas [8,11].…”