The relationship of the canine acanthomatous epulis to ameloblastoma

This paper compares the microscopic features and clinical behaviour of the acanthomatous epulis in dogs with those of ameloblastoma in human beings. The acanthomatous epulis has similar microscopic features to one histological variant of human ameloblastoma, the acanthomatous ameloblastoma. Moreover, its clinical behaviour is equivalent to that of intraosseous ameloblastoma in human beings, not of the human peripheral (extraosseous) ameloblastoma, as has been suggested. The stroma of acanthomatous epulides varies and does not always resemble periodontal ligament, a feature that in dogs has been used to distinguish them from ameloblastomas. It is concluded that the acanthomatous epulis (1) is an ameloblastoma, (2) arises from the gingival epithelium in some cases, but (3) may also arise intraosseously and then break out of bone. We recommend the term canine acanthomatous ameloblastoma as being appropriate for this lesion.

The histological nature of epulides in dogs

The histological characteristics of a series of 154 oral tumours with the clinical appearance of epulides in 129 dogs were reviewed. Diagnoses were based on current criteria in human oral pathology and compared with the original diagnoses. The histological findings suggested that the majority of epulides in the dog can be classified as focal fibrous hyperplasia (43.5 per cent), peripheral ameloblastoma (17.5 per cent), peripheral odontogenic fibroma (WHO type) (16.9 per cent) and pyogenic granuloma (1.95 per cent). In addition, a number of other odontogenic tumours (1.95 per cent) and non-odontogenic tumours (18.2 per cent) such as fibrosarcoma and squamous cell carcinoma, which are not traditionally associated with the clinical appearance of an epulis, were diagnosed. Of 74 lesions that were previously diagnosed as fibromatous and ossifying epulides, 50 (68 per cent) were reclassified as focal fibrous hyperplasia and 21 (28 per cent) as peripheral odontogenic fibroma (WHO type). The majority of lesions (76 per cent), which were originally classified as acanthomatous epulis, were found to be peripheral ameloblastoma. In addition, three squamous cell carcinomas, two rare odontogenic tumours and two cases of focal fibrous hyperplasia were diagnosed in this classification. It was concluded that, as in man, the term epulis is a clinically descriptive term and that the renal nature of these lesions should be determined histologically.

Fibromatous epulis in dogs and peripheral odontogenic fibroma in human beings: two equivalent lesions

This article compares the clinical and histopathologic features of the peripheral odontogenic fibroma in human beings and the fibromatous epulis in dogs. They are apparently equivalent lesions. Both are odontogenic tumors of limited growth potential that do not recur if adequately excised; both occur in middle and late adulthood of the species concerned. The one difference is that the peripheral odontogenic fibroma is a rare condition, whereas the canine fibromatous epulis is common.

Fordyce's granules of the incisor and molar gingiva in F344 rats

Fordyce's granules were observed in the gingiva of the upper incisor and molar teeth in F344 rats. The data were based on 734 males and 722 females that were used as control and treated animals in 26-week, 65-week, and 2-year studies by the National Toxicology Program. The incidence of Fordyce's granules was markedly different when comparing sex, age, and site of the lesion. Fordyce's granules were very common in the midsagittal gingiva of the upper incisor in males and increased in incidence with age (34.2, 50, and 56.3% in 26-week, 65-week, and 2-year studies, respectively). The granules of the incisor gingiva were rare in females (0,0, and 2.8% in 26-week, 65-week, and 2-year studies, respectively). Fordyce's granules of the molar gingiva were very rare in both sexes and were found only in 9/734 (1.2%) males and in 3/722 (0.4%) females. Only three unilateral granules of the molar were grossly recognized as focal swelling of the gingiva or a white nodule with a huge cyst in the third upper molar. Histologically, Fordyce's granules were arranged as a collection of sebaceous glands unassociated with hair follicles. In addition, the granules of the molar gingiva were associated with cystically dilated ducts filled with sebum. Ultrastructurally, the sebaceous cells were characterized by varying numbers of cytoplasmic lipid droplets and occasional desmosome and hemidesmosome formation. Fordyce's granules previously reported in rats of other strains were also reviewed and compared with those in F344 rats in regard to incidence, location, and age.

Feline oral neoplasia: a ten-year survey

A retrospective histological study was conducted on 371 neoplasms of the oral cavity in cats. Oral neoplasia accounted for 10% of feline neoplasms identified during the survey period. Eighty-nine percent of the oral neoplasms were malignant. Twenty different oral neoplasms were found. The most common were squamous cell carcinoma (61.2%), fibrosarcoma (12.9%), and fibromatous epulis of periodontal ligament origin (7.8%).

Wide local excision of acanthomatous epulides in the dog

Twenty-five dogs bearing acanthomatous epulides of the oral cavity underwent tumor resection by wide local excision. The surgical procedures included rostral mandibulectomy, removal of the mandibular body, premaxillectomy, and partial maxillectomy. Postoperative complications were rare, and local recurrence was not encountered in any dogs over periods of 1 to 6 1/2 years (median, 22 months). The authors conclude from the high incidence of local recurrence after simple excision through the tumor margins and the potential for malignant transformation after irradiation that wide surgical resection is the technique of choice for the management of acanthomatous epulis.

Lobular capillary haemangiomas in two calves

Lobular capillary haemangiomas in the gingiva near the mandibular incisor region of two 6-month-old calves are described.

Papillary squamous cell carcinoma in three young dogs

Papillary squamous cell carcinomas were located on the gingiva of 3 young dogs. The tumors locally invaded the soft tissues of each dog, and invaded bone in 2 dogs. Surgical excision was unsuccessful in eliminating 2 of the tumors. Surgery and radiotherapy were effective, and recurrence has not been observed in 39 months in 1 dog, 32 months in a second, and 10 months in a third. Superficially, the oral masses resembled papillomas, which are known to be caused by viruses. Cytopathologic indication of productive infection was not evident, and papillomavirus antigens could not be detected by immunohistochemical methods. Electron microscopy failed to identify viral particles in 2 of the tumors. High and low molecular weight DNA extracts from 2 of the tumors contained no detectable papillomavirus genome when probed under conditions of either high or low stringency by Southern blot hybridization with a cloned canine oral papillomavirus genome.

Classification and behaviour after surgery of canine 'epulides'

Seventy-five surgically excised canine gum neoplasms, which had previously been diagnosed as epulis or ameloblastoma, were reclassified on the basis of their presumed tissue of origin. They included 42 tumours of fibroblastic origin, which contained small foci of odontogenic epithelium and were classified as peripheral odontogenic fibroma, whilst 31 epithelial tumours were classified as basal cell carcinomas arising from the gum epithelium. Two epithelial tumours which apparently arose within the bone of the mandible and were not connected with the surface mucosa were classified as ameloblastomas. Follow-up studies after surgery revealed a recurrence rate of 17 per cent for the odontogenic fibromas and 50 per cent for basal cell carcinomas. Neither of the ameloblastomas, which were initially treated by radical excision, recurred locally and no metastases were detected from any of these tumours.

[Treatment of malignant epulis in dogs]

The successful radiotherapy of malignant epulis in a 12 year-old Dachshund is discussed. Regrowth of the tumour, which was first removed by surgery, was treated with radiotherapy over a period of 36 days in 3 fractions. The total dose was 1800 rads. The lesion healed uneventfully. After 600 days, there was still no new growth but only scar tissue to be seen.

Ameloblastoma and keratinizing ameloblastoma in dogs

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 th 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.

Radiotherapy and hyperthermia in the treatment of fibrosarcomas in the dog

Ten dogs with oral or external nasal fibrosarcoma were treated sequentially with orthovoltage radiation and radiofrequency (RF)-induced hyperthermia. Total radiation doses ranged from 3,200 to 4,800 rad given in 8 to 12 fractions of 400 rad. Immediately after 2 to 4 radiation treatments, hyperthermia was given. Six oral fibrosarcomas were heated to 50 C for 30 sec, using a hand-held RF generator. Four nasomaxillary fibrosarcomas were heated to 43 C for 30 minutes, using a 500-kHz RF generator. Hyperthermia of 50 C resulted in tumor necrosis and infection in 3 dogs and fatal septicemia in 1 dog. Nine of 10 tumors responded to therapy. One year after therapy, 5 dogs were free of disease. Tumor regrowth occurred in 5 dogs. Mean time to tumor regrowth and mean survival time of all dogs were 343 and 398 days, respectively. The results suggested that sequential radiation-hyperthermia is an effective therapeutic regimen for canine fibrosarcoma. It was concluded that this modality not only may be beneficial in the treatment of canine tumors but may be useful for designing new therapeutic approaches to similar tumors in man.

Adamantinoma--histogenesis and differentiation from the periodontal fibromatous epulis and squamous cell carcinoma

Six cases of oral adamantinoma, four in dogs, two in cats, are described. This is a rare tumor which arises from vestigial layers of the dental laminae in the gingiva, particularly of the mandible. Care must be exercised in not confusing this locally aggressive lesion with the much more common squamous cell carcinoma.