Odontogenic Fibromyxoma in a Cat: First Confirmed Case in This Species.

An inflammatory gingival mass surrounding resorbing teeth was diagnosed via biopsy in a 9-year-old domestic shorthair cat. A dorsal rim excision was performed to remove the entire mass with associated teeth and bone. Histopathological diagnosis of the en bloc tissue revealed an odontogenic fibromyxoma. Extensive literature review revealed few case reports of companion animals with this neoplasm, and none in a feline patient. This report documents the clinical presentation, diagnostic differentials, surgical therapy, and long-term follow-up of an odontogenic fibromyxoma in a cat.

Surgical resection of peripheral odontogenic fibromas in African pygmy hedgehog (Atelerix albiventris): a case study.

BACKGROUND: Neoplastic lesions of the mammary gland, lymph nodes, or oral cavity in African pygmy hedgehogs (Atelerix albiventris) are common in captive animals. Chemotherapy and radiotherapy protocols have not yet been established for the African pygmy hedgehog. Thus, surgical resection is the current treatment of choice in this species. CASE PRESENTATION: A 5-year-old male African pygmy hedgehog showed multiple erythematous, round small tumors located in the oral cavity, on both sides of maxilla. The treatment of choice was surgical resection of tumors using a surgical knife under general anesthesia. Excised neoplastic lesions were diagnosed as peripheral odontogenic fibroma by histopathology. Six months after surgery relapse of tumors in the oral cavity was not observed. CONCLUSIONS: The treatment adopted in this case report is safe for the patient and provides the best solution for mild proliferative lesions of the oral cavity. To our knowledge this is the first report of surgical resection of oral tumors (peripheral odontogenic fibroma) in the African pygmy hedgehog.

Clinicopathological features of peripheral odontogenic fibromas in dogs and risk factors for their laboratory diagnosis.

OBJECTIVES: To explore clinicopathological features of peripheral odontogenic fibromas in dogs and risk factors for their diagnosis. MATERIALS AND METHODS: Data of cases with a histopathological diagnosis of peripheral odontogenic fibromas were obtained from a UK-based diagnostic laboratory and retrospectively reviewed. Prevalence amongst all biopsy submissions was assessed using binomial tests and Clopper-Pearson intervals. Age at diagnosis was assessed using t-test for independent samples. Lesion location, sex, and neuter status were assessed using χ2 and post hoc binomial tests. Breed odds ratios were calculated using univariable logistic regression modelling. RESULTS: The prevalence of peripheral odontogenic fibromas amongst all biopsy submissions was 2.8% (1001 of 35,328, 95% confidence interval [CI]: 2.7 to 3.0). The mean (sd) age was 8.1 (±2.7) years. The most affected quadrant was the rostral maxilla (40.1%). The ratio of maxillary to mandibular lesions was 1.3:1 (95% CI: 1.1 to 1.5), and for cases of multiple peripheral odontogenic fibromas the ratio of maxillary to mandibular lesions was 2.4:1 (95% CI: 1.1 to 5.6). Males had 1.2 times the odds of suffering of peripheral odontogenic fibromas compared to females (odds ratio [OR]: 1.2, 95% CI: 1.1 to 1.4). Neutering was associated with an increased risk of diagnosis (OR: 1.6, 95% CI: 1.3 to 1.9). Breeds with increased odds of peripheral odontogenic fibromas compared to crossbreed dogs included boxers (OR: 3.78, 95% CI: 2.80 to 5.09), border terriers (OR: 3.21, 95% CI: 2.10 to 4.91) and Basset Hounds (OR: 3.18, 95% CI: 1.58 to 6.44). Breeds with increased odds of multiple simultaneous peripheral odontogenic fibromas compared to crossbreed dogs included: Boxers (OR: 12.02, 95% CI: 7.13 to 20.24), border terriers (OR: 5.05, 95% CI: 2.32 to 11.43) and Staffordshire Bull terriers (OR: 2.42, 95% CI: 1.33 to 4.41). CLINICAL SIGNIFICANCE: Knowledge of clinicopathological features and at-risk breeds for peripheral odontogenic fibroma development can assist clinicians with making a diagnosis. The identification of risk factors provides targets for future research investigating peripheral odontogenic fibroma pathogenesis.

Nonossifying fibroma in the mandible of a goat.

An 8-year-old male Nubian goat was presented with a peracute history of straining to urinate and unilateral mandibular swelling. At necropsy, the rostral half body of the left mandible was distorted by fusiform swelling that, on sagittal section, had marked medullary bone loss and replacement with a well-demarcated fibrous mass. Histologically, the mass comprised streaming spindloid cells with whorls and storiform patterns, interspersed with numerous multinucleated giant cells. Bone formation was not present in the neoplasm. The mandibular mass was diagnosed as nonossifying fibroma, a relatively common tumor in children but seldom reported in domestic animals.

Clinicopathologic characterization of odontogenic tumors and focal fibrous hyperplasia in dogs: 152 cases (1995-2005).

OBJECTIVE: To characterize clinicopathologic features of the most common odontogenic tumors and focal fibrous hyperplasia (FFH) in dogs. DESIGN: Retrospective case series. ANIMALS: 152 dogs evaluated for oral tumors of possible odontogenic origin at the William R. Pritchard Veterinary Medical Teaching Hospital of the University of California-Davis between 1995 and 2005. PROCEDURES: Information was collected from records, including dog breed, age, reproductive status, and location of lesion in the oral cavity. Histologic slides pertaining to each dog were reviewed by 3 investigators. Data regarding clinicopathologic features of the 3 most common lesions (canine acanthomatous ameloblastoma [CAA], peripheral odontogenic fibroma [POF], and FFH) were summarized. RESULTS: 152 dogs with odontogenic tumors or FFH were identified. Sixty-eight (45%) dogs had CAA, 47 (31 %) had POF, 24 (16%) had FFH, and 13 (9%) had other odontogenic tumors. Canine acanthomatous ameloblastoma was present most commonly in the rostral aspect of the mandible, with POF and FFH more common in the rostral aspect of the maxilla. Males and females were equally represented among dogs with CAA and FFH. Castrated males were overrepresented among dogs with POF. Golden Retrievers, Akitas, Cocker Spaniels, and Shetland Sheepdogs were overrepresented among dogs with CAA. No breed predisposition was detected for FFH or POF. Dogs with FFH had a greater mean age at initial evaluation than did dogs with CAA or POF. CONCLUSIONS AND CLINICAL RELEVANCE: CAA, POF, and FFH have distinct clinical patterns that may help clinicians and pathologists identify such lesions more readily.

Mixed odontogenic tumors in four young dogs: ameloblastic fibroma and ameloblastic fibro-odontoma.

Ameloblastic fibroma (AF) and ameloblastic fibro-odontoma (AFO) are mixed odontogenic tumors (odontogenic tumors with induction) that are reported only rarely in dogs. These tumors are histologically complex and, to a degree, recapitulate the early stages of tooth development, comprising 2 types of tissue: neoplastic odontogenic epithelium, and induced ectomesenchyme (dental pulp). AFOs are distinguished from AFs by the additional presence of hard dental matrices such as dentin. Herein, we describe the key diagnostic features of AF and AFO in 4 young dogs.

Diagnosis and management of odontogenic myxoma in a dog.

A three-year-old Jack Russell terrier dog was presented with a large gingival mass of the right mandible extending from the fourth premolar to the first molar teeth. Radiographic examination of the expansile mass revealed moth-eaten, honeycomb-like lyses of the mandible and extended into the mandibular alveolar canal based on computed tomography. The histopathological diagnosis of the biopsy was odontogenic fibromyxoma. Mandibulectomy with resection of the associated soft tissues was performed. Surgical management was curative with no clinical signs of disease 2-years after treatment. These neoplasms are slow growing, locally destructive tumors of odontogenic origin that have been described in the jaw of only one dog. In this paper, the clinico-radiological and pathologic features, diagnostic modalities as well as the factors that might influence treatment outcome of odontogenic myxomas are discussed. These odontogenic tumors are currently excluded from the WHO classification of odontogenic tumors in domestic animals and inclusion in future classifications systems is proposed.

Ameloblastic fibroma in an alpine chamois (Rupicapra rupicapra).

Spontaneous odontogenic tumors are neoplasms characterized by a mixed odontogenic ectomesenchymal and odontogenic epithelial origin; they are rare in both humans and animals. A 3-year-old male Alpine Chamois (Rupicapra rupicapra) was found dead in north-west Italy, and was referred for the necropsy to the Department of Veterinary Sciences of the University of Turin (Italy). At the external examination a 10 × 8 cm, exophytic, red-pink, smooth, firm and ulcerated mass was observed on the inferior lip. Histologically the tumor was characterized by spindle shaped cells arranged in bundles in an abundant hyaline matrix. Multifocal and rare chords of odontogenic epithelium mixed with rare melanocytes that penetrate the neoplasia were visible. Immunohistochemistry showed a clear cytokeratin positivity of epithelial clusters. Macroscopical, histological and immunohistochemical findings were consistent with a diagnosis of locally infiltrative ameloblastic fibroma. To our best knowledge, this is the first report of this tumor in a wild ungulate and in Alpine Chamois.

Aggressive fibromatosis in a cat.

A case of aggressive fibromatosis (extra-abdominal desmoid) found in a 9-month-old male mixed breed cat is described. The right forearm was almost completely effaced by fibrous tissue and there were some tumours in the area from the shoulders to the mandible. These tumour-like tissues were composed of abundant collagen fibres and sparse numbers of well-differentiated fibroblasts, whereas their growing pattern was aggressive and non-encapsulated. There was dense growth of immature fibroblasts and multinucleated giant cells in some areas. Vimentin immunohistochemistry and electron microscopy suggested that the giant cells had close relation to the fibroblasts, and such areas may be the sites of cell proliferation. This case is different from nodular fasciitis and may be a proliferative disorder induced by feline oncogenic retrovirus.

Oral fibroma in a captive python.

A massive growth in the lower jaw of an Indian python (Python molurus) was diagnosed from biopsy samples as a fibroma. Moderately satisfactory treatment was achieved by surgical excision.

Lip fibromas associated with retrovirus-like particles in angel fish.

Fibromas were observed on the lips of adult female and juvenile angel fish (Pterophyllum scalare) from 3 Florida farm populations. Tumor prevalence in each population was < 1%. Affected fish were clinically normal except for those with large tumors, which had weight loss caused by physical obstruction of food intake. Fibromas originated as elevated masses from the mucocutaneous junction near the midline of the upper and/or lower lips. Characteristic features included dense fibrous stroma covered by thickened, stratified squamous epithelium, numerous intraneoplastic teeth, and scattered foci of stromal inflammation. Electron microscopy revealed intracytoplasmic type-A retrovirus-like particles in stromal cells from all tumors. Attempts to transmit fibromas, using a cell-free tumor ultrafiltrate, were unsuccessful. The relationship of the intraneoplastic viral particles to the development of lip fibromas in angel fish is uncertain.

Rostral mandibulectomy in five horses.

Rostral mandibulectomy with primary gingival closure was performed in 5 horses with rapidly growing or bleeding mandibular tumors. The technique involved preservation of the most caudal portion of the mandibular symphysis to maintain stability. There were no surgical complications or recurrences, and the cosmetic and functional results were good. The histopathologic diagnosis of all the tumors was ossifying fibroma. Rostral mandibulectomy affords a simple and effective technique of treating tumors of the rostral portion of the mandible in horses.

Fibroblastic tumor of the premaxilla in two horses.

In 2 horses with rapidly growing, locally destructive tumors of the premaxilla, there was major disruption and displacement of some incisor teeth, with radiographic evidence of disruption of the premaxilla at the base of the tumors. In horse 1, most of the tumor was removed by incising it at its base, and the tumor bed was treated cryosurgically with 3 freeze-thaw cycles, using liquid nitrogen. The area healed by 2nd intention. The tumor was found to be a benign fibroblastic tumor, possibly a fibroma. After 4 years, there has been no recurrence. Horse 2 was euthanatized on the basis of a tentative biopsy diagnosis of osteogenic sarcoma. Postmortem studies supported a diagnosis of fibrosarcoma without metastasis.

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.

Expression of cytokeratins in the epithelium of canine odontogenic tumours.

Odontogenic tumours are considered to be relatively rare; however, several histologically distinct types have been identified in dogs. The more common canine odontogenic tumours are peripheral odontogenic fibroma and canine acanthomatous ameloblastoma. The expression of cytokeratins (CKs) has been established for the human dental germ and odontogenic tumours. The aim of the present study was to describe the immunohistochemical expression of a panel of CKs in the epithelium of the canine dental germ, normal gingiva and odontogenic tumours arising in this species. Samples from 20 odontogenic tumours, 12 tooth germs and three normal gingival tissues were obtained. Each sample was stained with haematoxylin and eosin and subjected to immunohistochemistry for CK expression. The typical expression pattern of CKs in the odontogenic epithelium and gingiva of dogs was CK14 and CK5/6. CKs 7, 8, 18 and 20 were generally absent from the canine dental germ, gingiva and odontogenic tumours. Dogs and man therefore exhibit similar CK expression in the odontogenic epithelium.

The fibrous epulis in the dog.

The pathology of the fibrous epulis in the dog is described and found to be comparable to that seen in humans. Emphasis is placed on the apparent relationship between the hyperplasia of the covering epithelium and calcification of the connective tissue component, and a theory to explain this relationship is proposed.

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.