The so-called calcifying epithelial odontogenic tumour in dogs and cats (amyloid-producing odontogenic tumour)

Classification of amyloidosis and protein misfolding disorders in animals 2024: A review on pathology and diagnosis

Amyloidosis is a group of diseases in which proteins become amyloid, an insoluble fibrillar aggregate, resulting in organ dysfunction. Amyloid deposition has been reported in various animal species. To diagnose and understand the pathogenesis of amyloidosis, it is important to identify the amyloid precursor protein involved in each disease. Although 42 amyloid precursor proteins have been reported in humans, little is known about amyloidosis in animals, except for a few well-described amyloid proteins, including amyloid A (AA), amyloid light chain (AL), amyloid β (Aβ), and islet amyloid polypeptide-derived amyloid. Recently, several types of novel amyloidosis have been identified in animals using immunohistochemistry and mass spectrometry-based proteomic analysis. Certain species are predisposed to specific types of amyloidosis, suggesting a genetic background for its pathogenesis. Age-related amyloidosis has also emerged due to the increased longevity of captive animals. In addition, experimental studies have shown that some amyloids may be transmissible. Accurate diagnosis and understanding of animal amyloidosis are necessary for appropriate therapeutic intervention and comparative pathological studies. This review provides an updated classification of animal amyloidosis, including associated protein misfolding disorders of the central nervous system, and the current understanding of their pathogenesis. Pathologic features are presented together with state-of-the-art diagnostic methods that can be applied for routine diagnosis and identification of novel amyloid proteins in animals.

Clinical, Radiographic and Histologic Evaluation of 40 Cystic Oral Lesions in 37 Cats

Feline cystic oral lesions are uncommon and include odontogenic cysts and cystic odontogenic tumors. Accurate diagnosis requires close collaboration between the clinician's clinical and radiographic findings and the pathologist's histologic interpretations. The odontogenic cysts identified in this series include a periapical cyst, dentigerous cysts and a type of unclassified collateral cyst that appears to be a previously undefined, distinct entity in cats (UCC). Many of the cysts (52%) were unable to be classified due to insufficient diagnostic information, which often related to the associated tooth being unavailable for evaluation. Cystic odontogenic tumors included ameloblastomas, amyloid producing ameloblastomas (APA), and feline inductive odontogenic tumors (FIOT). The purpose of this case series was to assess correlations between clinical and radiographic findings, histopathologic interpretation and signalment to identify common characteristics and provide recommendations for clinicians and pathologists to optimize diagnostic efficiency and accuracy for cystic oral lesions in cats.

Identification of Ameloblastin as an Amyloid Precursor Protein of Amyloid-Producing Ameloblastoma in Dogs and Cats

Amyloid-producing ameloblastoma (APAB) is characterized by abundant amyloid deposits in ameloblastoma, but the amyloid precursor protein is unknown. To explore this, we conducted histopathologic and proteomic analyses on formalin-fixed and paraffin-embedded samples from five cases of APAB (three dogs and two cats). Histologically, the samples exhibited a proliferation of the odontogenic epithelium, with moderate to severe interstitial amyloid deposits. By using Congo red and polarized light, the amyloid deposits were found to show characteristic birefringence. Amyloid deposits were dissected from tissue sections and analyzed by LC/MS/MS, and high levels of ameloblastin were detected in all tissues. Mass spectrometry also revealed that the N-terminal region of ameloblastin is predominantly present in amyloid deposits. Immunohistochemistry was performed using two anti-ameloblastin (N terminal, middle region) antibodies and showed that amyloid deposits were positive for ameloblastin N terminal but negative for ameloblastin middle region. These results suggest that ameloblastin is the amyloid precursor protein of APABs in dogs and cats, and the N-terminal region may be involved in the amyloidogenesis of ameloblastin.

Case Report: Amyloid-Producing Odontogenic Tumor With Pulmonary Metastasis in a Spinone Italiano-Proof of Malignant Potential

A 1-year-old male Spinone Italiano dog was treated for an amyloid-producing odontogenic tumor on the right maxilla with a cytoreductive surgery followed by a definitive radiation protocol. Six years later, the dog presented for a new mass on the rostral mandible as well as a lung nodule without recurrence of the original maxillary tumor. Both the mandibular mass and the lung nodule were histologically confirmed to be amyloid-producing odontogenic tumor based on the appearance of sheets and cords of the odontogenic epithelium disrupted by amorphous extracellular amyloid. This case illustrates the metastatic potential for amyloid-producing odontogenic tumor in dogs and asynchronous occurrence of multiple APOTs in the oral cavity.

Diagnosis and Treatment of an Odontogenic Epithelial Tumor in a Dog With Features of Squamous Odontogenic Tumor

A 9-year-old standard poodle presented for a comprehensive oral health assessment and treatment, at which time a left rostral mandibular swelling was recognized. The mass was biopsied and eventually excised by a left rostral mandibulectomy en bloc resection. Histopathology supported the diagnosis of a benign, intraosseous, epithelial tumor that was otherwise unclassified. The clinical, radiological, and histological features of this case are similar to those reported for squamous odontogenic tumor (SOT) in humans. This case study relays the diagnosis, treatment, and follow-up of the first SOT-like tumor in a dog.

Maxillary and Mandibular Peripheral Odontogenic Fibromas (Fibromatous Epulides of Periodontal Ligament Origin) in a Cat

Peripheral odontogenic fibroma (POF) is an uncommon finding in the mouth of cats. Few cases have been reported in the literature. The present report describes an adolescent, male-castrated domestic shorthair cat with POFs at the rostral upper and lower jaws that were treated via marginal excision including removal of underlying bone. Despite the high incidence of recurrence reported in the literature, recheck examinations up to 11 months postoperatively did not show regrowth of the gingival masses. Thus, marginal excision including removal of underlying bone appears to be a viable treatment option for POF in cats.

Feline Oral Squamous Cell Carcinoma: Clinical Manifestations and Literature Review

Squamous cell carcinoma (SCC) is the most commonly encountered malignant oral tumor in cats. The etiology of this locally invasive tumor is likely multifactorial. Several risk factors have been identified, including the use of flea collars, and a history of feeding canned food and canned tuna. Clinical signs vary depending on tumor location. The tumor commonly arises from the gingiva and mucosa of the maxilla, mandible, tongue, sublingual area, or tonsillar region. Maxillary SCC commonly presents clinically as an ulcerative lesion, whereas mandibular SCC is commonly proliferative, expansile, and firm. Lingual/sublingual SCC may be ulcerative, necrotic, infiltrative, or proliferative. In general, feline oral SCC is an invasive and malignant neoplasm regardless of its location. Surgery, radiation therapy, chemotherapy and combinations thereof have been attempted with rarely a satisfactory response. Currently, cures are obtained only in a small subset of cats whose tumors are amenable to complete resection, or where resection with microscopic residual disease is followed by definitive radiation therapy. A multimodal treatment approach likely offers the best chance of success. For cats with advanced disease, palliative care may improve patients' quality of life, albeit transiently. Sequelae associated with tumor progression and local tissue destruction often result in euthanasia of feline patients with oral SCC.

Nomenclature and Classification of Odontogenic Tumors - Part I: Historical Review

Odontogenic tumor nomenclature and classification is frustrating for both physicians and veterinarians. There has been and continues to be an evolution of the terms and taxonomy used in veterinary and human literature. In this historical review, we aim to provide veterinarians a fundamental basis for understanding how the etymology for odontogenic tumors has evolved over the past two centuries.

Nomenclature and Classification of Odontogenic Tumors - Part II: Clarification of Specific Nomenclature

Accurate identification of odontogenic tumors is critical for productive communication and an important foundation for useful comparative epidemiologic studies of odontogenic tumors in both domestic animals and humans. This manuscript illuminates the subject of veterinary odontogenic tumor nomenclature and will serve as a foundation for future updates in nomenclature and classification of odontogenic tumors.

One hundred two tumors in 100 goats (1987-2011)

Of 1146 caprine necropsy or biopsy specimens submitted from 1987 through 2011 to the Veterinary Diagnostic Laboratory at Oregon State University, 100 goats (8.7%) had 102 tumors. Detailed records were available for 89 cases. Fifty-five goats were female, 17 were castrated males, and 12 were intact males. Breeds included 21 Nubian, 16 Pygmy, 10 Pygora, 8 Alpine, 4 Angora, 4 Saanen, 2 Toggenburg, and 9 crossbred goats. Dwarf, Nubian, and Saanen goats were overrepresented and Alpine and Boer goats underrepresented among cases with neoplastic disease in comparison to submissions overall. Age ranged from 7 months to 19 years (median, 7 years). Histopathology was performed on 97 tumors. Lymphoma (n = 17) was the most common tumor, followed by cutaneous squamous cell carcinoma (n = 10) and thymoma (n = 9). Most lymphomas were multicentric. All 7 mammary neoplasms were adenocarcinomas. Five of 7 vascular proliferations were hemangiosarcomas. All 4 melanocytic tumors were classified as (malignant) melanoma. Rarely reported caprine tumors included a choroid plexus carcinoma, 2 rhabdomyosarcomas, and 3 pheochromocytomas. Cutaneous round cell tumors were provisionally diagnosed as 2 histiocytomas and 5 mast cell tumors. Single cases of previously unreported caprine tumors included amyloid-producing odontogenic tumor, myxosarcoma, sebaceous carcinoma, apocrine sweat gland adenoma, and thyroid carcinoma. Nonneoplastic entities included 2 cases of mammary fibroadenomatous hyperplasia and single cases of vascular hamartoma, cervical adenomatous hyperplasia, and cervical leiomyofibromatosis. The results of this 25-year retrospective study indicate that lymphoma in particular and tumors in general are common in goats.

Immunohistochemical and biochemical evidence of ameloblastic origin of amyloid-producing odontogenic tumors in cats

Amyloid-producing odontogenic tumors (APOT) are rare, and in cats, the histogenesis of the amyloid remains undetermined. In the present study, APOTs in 3 cats were characterized by immunohistochemistry, and the amyloid components analyzed using tandem mass spectrometry. Antiameloblastin antibodies labeled both neoplastic epithelial cells and amyloid in all cases. Neoplastic epithelial cells had strong, diffuse immunoreactivity to antibodies against cytokeratin AE1/AE3, cytokeratin 14, and cytokeratin 19 in all cases and focal immunoreactivity to nerve growth factor receptor antibodies in 2 of 3 cases. Amyloid and some tumor stromal cells were weakly positive for laminin. Calretinin, amelogenin, S100, and glial fibrillary acidic protein antibodies did not label neoplastic epithelial cells or amyloid. Extracted amyloid peptide sequences were compared to the porcine database because the cat genome is not yet complete. Based on this comparison, 1 identical ameloblastin peptide was detected in each tumor. These results suggest that feline APOTs and the amyloid they produce are of ameloblastic lineage.

Oral Masses in Two Cats

Incisional biopsies from the oral cavity of 2 adult cats were submitted for histological investigation. Cat No. 1 showed a solitary well-circumscribed neoplasm in the left mandible. Cat No. 2 demonstrated a diffusely infiltrating neoplasm in the left maxilla. Both tumors consisted of medium-size epithelial cells embedded in a fibrovascular stroma. The mitotic index was 0 to 1 mitosis per high-power field. The epithelial cells showed an irregular arrangement forming nests or streams in cat No. 1, whereas a palisading growth was noted in cat No. 2. Both tumors, especially that of cat No. 1, showed multifocal accumulations of amyloid as confirmed by Congo red staining and a distinct green birefringence under polarized light, which lacked cytokeratin immunoreactivity as well as and AL and AA amyloid immunoreactivity. In addition, the amyloid in cat No. 2 was positive for the odontogenic ameloblast-associated protein, formerly termed APin. In sum, both cats suffered from an amyloid-producing odontogenic tumor, but their tumors varied with respect to morphology and type of amyloid produced.

Biochemical and immunohistochemical characterization of the amyloid in canine amyloid-producing odontogenic tumor

The amyloid of canine amyloid-producing odontogenic tumor (APOT) was evaluated biochemically and immunohistochemically. The N-terminal amino-acid sequence of purified amyloid protein from a canine APOT was strikingly similar to the sequence in both rat ameloblastin and porcine sheathlin. Immunohistochemically, the amyloid in APOT from 9 dogs was strongly reactive with anti-rat ameloblastin, anti-porcine sheathlin, and anti-canine APOT amyloid and weakly reactive with anti-porcine amelogenin but negative for antibodies to cytokeratins, vimentin, desmin, alpha-smooth muscle actin, amyloid A, glial fibrillary acidic protein, or S100 protein. The neoplastic epithelial cells of APOT were focally reactive with antibodies to ameloblastin, sheathlin, amelogenin, and canine APOT amyloid. The similarity in amino-acid sequence of the amyloid protein of canine APOT to that of enamel proteins, such as ameloblastin, sheathlin, and amelogenin, and the expression of these antigens in both APOT amyloid and in the neoplastic cells suggest that the amyloid of canine APOT is derived from enamel proteins secreted by ameloblasts.

Amyloid-producing odontogenic tumor and its immunohistochemical characterization in a Shih Tzu dog

A 10-year-old, male, Shih-Tzu dog presented with swelling of the right lower jaw caused by a mass arising from the right mandibular gingiva. Radiographic examination revealed bone lysis of the right wing of the mandible. Histopathologically, the growth was characterized by indistinctly lobulated nests, islands, and strands of proliferating odontogenic and squamous epithelial cells, intermingled in close association with large numbers of irregular extracellular deposits of amyloid and amorphous calcified substance. Immunohistochemically, both epithelial components stained strongly positive for cytokeratin (AE1/AE3); the squamous epithelial cells also reacted strongly with neuron-specific enolase (NSE) and S-100 protein, whereas the odontogenic epithelial cells displayed weak immunoreactivity to NSE and partial reactivity to S-100 protein. The amyloid deposits were AE1/AE3-negative. The growth was diagnosed as an amyloid-producing odontogenic tumor.

Amyloid-producing odontogenic tumour (calcifying epithelial odontogenic tumour) in the mandible of a Bengal tiger (Panthera tigris tigris)

A 13-year-old male tiger (Panthera tigris tigris) had a marked mandibular swelling noticed 12 months earlier and associated with progressive anorexia and weight loss. Radiological and post-mortem examination revealed a mass (13x15 cm) which was firm and poorly defined, with destruction of the adjacent bone tissue. Histologically, the mass was poorly demarcated, with infiltrative growth, and composed of nests, cords and islands of epithelial cells with characteristic basal cell features. Also observed were extensive squamous metaplasia, ghost cells, stellate reticulum, and fibroblastic connective tissue stroma containing inflammatory cells. A prominent feature of this tumour consisted of abundant nodular deposits of congophilic amyloid-like material with partial mineralization (Liesegang rings). Immunohistochemically, the neoplastic cells and the amyloid-like material were positive for pancytokeratin and negative for vimentin. The findings supported the diagnosis of an amyloid-producing odontogenic tumour (APOT), also known as calcifying epithelial odontogenic tumour in man and animals.

Protein folding pathology in domestic animals

Fibrillar proteins form structural elements of cells and the extracellular matrix. Pathological lesions of fibrillar microanatomical structures, or secondary fibrillar changes in globular proteins are well known. A special group concerns histologically amorphous deposits, amyloid. The major characteristics of amyloid are: apple green birefringence after Congo red staining of histological sections, and non-branching 7-10 nm thick fibrils on electron microscopy revealing a high content of cross beta pleated sheets. About 25 different types of amyloid have been characterised. In animals, AA-amyloid is the most frequent type. Other types of amyloid in animals represent: AIAPP (in cats), AApoAI, AApoAII, localised AL-amyloid, amyloid in odontogenic or mammary tumors and amyloid in the brain. In old dogs Abeta and in sheep APrPsc-amyloid can be encountered. AA-amyloidosis is a systemic disorder with a precursor in blood, acute phase serum amyloid A (SAA). In chronic inflammatory processes AA-amyloid can be deposited. A rapid crystallization of SAA to amyloid fibrils on small beta-sheeted fragments, the 'amyloid enhancing factor' (AEF), is known and the AEF has been shown to penetrate the enteric barrier. Amyloid fibrils can aggregate from various precursor proteins in vitro in particular at acidic pH and when proteolytic fragments are formed. Molecular chaperones influence this process. Tissue data point to amyloid fibrillogenesis in lysosomes and near cell surfaces. A comparison can be made of the fibrillogenesis in prion diseases and in enhanced AA-amyloidosis. In the reactive form, acute phase SAA is the supply of the precursor protein, whereas in the prion diseases, cell membrane proteins form a structural source. Abeta-amyloid in brain tissue of aged dogs showing signs of dementia forms a canine counterpart of senile dementia of the Alzheimer type (ccSDAT) in man. Misfolded proteins remain potential food hazards. Developments concerning prevention of amyloidogenesis and therapy of amyloid deposits are shortly commented.

Amyloid-producing odontogenic tumor in a Shih-Tzu dog

A 9-month-old male Shih-Tzu dog had a right mandibular tumor composed of strands, or nest-like proliferation of epithelial cells with abundant fibrous stroma characterized by spheroid to large nodular deposition of amyloid with Congo-red stain. Globule calcification was also seen throughout the tumor tissue and the spheroid depositions often had a concentrically laminated structure (Liesegang rings). The case was diagnosed as amyloid-producing odontogenic tumor in a dog.

A review of the expanding field of exotic animal oral health care--veterinary dentistry

This article reviews the clinical literature of the field of Veterinary Dentistry from its conception in the late 1960's to its rapidly expanding role today as an emerging clinical specialty practice in veterinary medicine. It defines eight dental sub-disciplines in contemporary veterinary oral health care from a practical point of view and provides information concerning standardization of key words searches, definition of terms, and use of the expanded Medical Subject Headings (MeSH) necessary for a comprehensive review of the rapidly expanding literature stored in electronic databases.

Ameloblastomas in cats: a critical evaluation of the literature and the addition of one example

The English language literature on feline ameloblastomas was evaluated. Seven acceptable cases were found and one additional example is added in this article. These rare tumors have occurred in cats over the age of 6 years, affected both sexes, both jaws, and various breeds. Two microscopic variants have so far been reported, namely the follicular pattern and the keratinizing pattern, which is similar to the keratinizing ameloblastoma in dogs. Ameloblastomas in cats have been confused in the past with two other feline odontogenic tumors: the inductive fibro-ameloblastoma (feline inductive odontogenic tumor) and the "calcifying epithelial odontogenic tumor" (amyloid-producing odontogenic tumor).

Epulides in the dog: a review

This article is based on a review of the literature and the study of pathology sections obtained from various veterinary pathology laboratories. Epulis is a non-specific, clinical designation for a localized, exophytic growth on the gingiva. Four reactive epulides occur in human beings, namely focal fibrous hyperplasia (fibrous epulis), pyogenic granuloma, peripheral giant cell granuloma (giant cell epulis), and peripheral ossifying fibroma (calcifying fibrous epulis). The first three also occur in dogs but only focal fibrous hyperplasia appears to be common. The peripheral ossifying fibroma has not yet been reported in dogs. Odontogenic tumors occurring on the gingiva (i.e., as epulides) are referred to as peripheral odontogenic tumors. Three types have been reported in dogs. One, the common fibromatous epulis, is equivalent to the rare peripheral odontogenic fibroma in human beings. Another, the acanthomatous epulis, appears to be a form of ameloblastoma but differs from the peripheral ameloblastoma in human beings in that it invades bone; its biological behavior is therefore that of the human intraosseous ameloblastoma. The third, a rare lesion, has been referred to in the veterinary literature as a calcifying epithelial odontogenic tumor, although it is not the canine counterpart of the human CEOT. The term, amyloid-producing odontogenic tumor, has been suggested as being appropriate for this lesion.