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==Introduction==

==Introduction==

Odontogenic tumors (OT) arise from remnants of the embryonic tissues destined to develop into teeth and associated structures. They originate from remnants of odontogenic epithelium (rests of Malassez and rests of Serres located within the periodontal ligament stroma and gingiva, respectively), odontogenic mesenchyme, or a combination of the cellular elements that comprise the tooth-forming apparatus. Clinical behavior ranges from hamartoma-like proliferations to benign and invasive neoplasms.  

Odontogenic tumors (OT) arise from remnants of the embryonic tissues destined to develop into teeth and associated structures. They originate from remnants of odontogenic epithelium (rests of Malassez and rests of Serres located within the periodontal ligament stroma and gingiva, respectively), odontogenic mesenchyme, or a combination of the cellular elements that comprise the tooth-forming apparatus. Clinical behavior ranges from hamartoma-like proliferations to benign and invasive neoplasms.  

Ameloblastoma is an epithelial tumor that originates from remnants of the dental organ (rests of Malessez), dental lamina, cells of epithelial origin lining odontogenic cysts or possibly from basal epithelial cells of the oral mucosa. It is a non-inductive (no effect on surrounding mesenchyme) tumor described in many domestic species, and occurs in the tooth-bearing areas of the mandible, maxilla and incisive bone. Because there is no production of enamel or dentin, it remains a soft tissue tumor and is considered the least differentiated of the epithelial OT. In spite of a benign appearance histologically in animals, ameloblastoma typically is a locally invasive, slow growing neoplasm that does not metastasise.

Ameloblastoma is an epithelial tumor that originates from remnants of the dental organ (rests of Malessez), dental lamina, cells of epithelial origin lining odontogenic cysts or possibly from basal epithelial cells of the oral mucosa. It is a non-inductive (no effect on surrounding mesenchyme) tumor described in many domestic species, and occurs in the tooth-bearing areas of the mandible, maxilla and incisive bone. Because there is no production of enamel or dentin, it remains a soft tissue tumor and is considered the least differentiated of the epithelial OT. In spite of a benign appearance histologically in animals, ameloblastoma typically is a locally invasive, slow growing neoplasm that does not metastasise.

   

   

*'''Central (or intraosseous) ameloblastoma''' - is a relatively uncommon odontogenic tumor in dogs and is rarely seen in cats. It usually manifests as a gross swelling with distortion of bone often resulting in tooth displacement or malocclusion. It is usually painless, with slow expansion and patients may be asymptomatic. Central ameloblastoma most often appears radiographically as an osteolytic, unilocular or multilocular cystic lesion around tooth roots, with well-defined, sclerotic margins. Jaw expansion usually occurs. Wide surgical excision (mandibulectomy or maxillectomy) is the treatment of choice and considered curative.

*[[Ameloblastoma, Central|'''Central (or intraosseous) ameloblastoma''']] - is a relatively uncommon odontogenic tumor in dogs and is rarely seen in cats. It usually manifests as a gross swelling with distortion of bone often resulting in tooth displacement or malocclusion. It is usually painless, with slow expansion and patients may be asymptomatic. Central ameloblastoma most often appears radiographically as an osteolytic, unilocular or multilocular cystic lesion around tooth roots, with well-defined, sclerotic margins. Jaw expansion usually occurs. Wide surgical excision (mandibulectomy or maxillectomy) is the treatment of choice and considered curative.

*'''Canine acanthomatous ameloblastoma''' - the second common histologic variant of ameloblastoma found in dogs is the canine acanthomatous ameloblastoma (CAA). This used to be called acanthomatous epulis and was distinguished biologically and histologically from other types of epulides by their tendency to infiltrate cancellous bone. The acanthomatous epulis was later recognized as a type of ameloblastoma and termed a peripheral ameloblastoma. The term peripheral ameloblastoma was later replaced by canine acanthomatous ameloblastoma, to differentiate it from the peripheral ameloblastoma in humans, which is a non-invasive tumor type.

*[[Acanthomatous Ameloblastoma|'''Canine acanthomatous ameloblastoma''']] - the second common histologic variant of ameloblastoma found in dogs is the canine acanthomatous ameloblastoma (CAA). This used to be called acanthomatous epulis and was distinguished biologically and histologically from other types of epulides by their tendency to infiltrate cancellous bone. The acanthomatous epulis was later recognized as a type of ameloblastoma and termed a peripheral ameloblastoma. The term peripheral ameloblastoma was later replaced by canine acanthomatous ameloblastoma, to differentiate it from the peripheral ameloblastoma in humans, which is a non-invasive tumor type.

*'''Acanthomatous ameloblastoma''' - also arises from remnants of odontogenic epithelium located in the gingiva (rests of Serres) in the tooth-bearing areas of the jaws. Although CAA is generally accepted as arising from gingival epithelium, it may also arise intraosseously and then break out of bone. The infiltration of bone distinguishes the CAA from central ameloblastoma. The radiographic pattern is dominated by bony infiltration, alveolar bone resorption and tooth displacement. Because acanthomatous ameloblastoma is locally aggressive and invades bone, bloc excision of the tumor with at least 1 cm of normal-appearing tissue is required to be curative. If the tumor is completely excised, the prognosis is excellent.

*'''Acanthomatous ameloblastoma''' - also arises from remnants of odontogenic epithelium located in the gingiva (rests of Serres) in the tooth-bearing areas of the jaws. Although CAA is generally accepted as arising from gingival epithelium, it may also arise intraosseously and then break out of bone. The infiltration of bone distinguishes the CAA from central ameloblastoma. The radiographic pattern is dominated by bony infiltration, alveolar bone resorption and tooth displacement. Because acanthomatous ameloblastoma is locally aggressive and invades bone, bloc excision of the tumor with at least 1 cm of normal-appearing tissue is required to be curative. If the tumor is completely excised, the prognosis is excellent.

====Amyloid-Producing Odontogenic Tumor====

====[[Amyloid-producing Odontogenic Tumour|Amyloid-Producing Odontogenic Tumor]]====

This OT type is rare in dogs and cats and presents as an ‘epulis’ on either jaw in patients between 8 to 13 years old. It has been previously referred to in veterinary literature as a calcifying epithelial odontogenic tumor. Amyloid-producing odontogenic tumor (APOT) appears as a gingival enlargement which grows by expansion. It is locally invasive but not does not metastasize. It often has a cystic appearance on radiographs and complete excision is considered curative.

This OT type is rare in dogs and cats and presents as an ‘epulis’ on either jaw in patients between 8 to 13 years old. It has been previously referred to in veterinary literature as a calcifying epithelial odontogenic tumor. Amyloid-producing odontogenic tumor (APOT) appears as a gingival enlargement which grows by expansion. It is locally invasive but not does not metastasize. It often has a cystic appearance on radiographs and complete excision is considered curative.

==Mesenchymal Tumours==

==Mesenchymal Tumours==

====Peripheral Odontogenic Fibroma====

====[[Peripheral Odontogenic Fibroma|Peripheral Odontogenic Fibroma]]====

Many of the tumors previously described as fibromatous and ossifying epulides have been reclassified as peripheral odontogenic fibroma (POF). Peripheral odontogenic fibroma is a slow growing, benign neoplasm, common in the dog and uncommon in the cat. The surface epithelium appears normal, and radiographic features vary according to the presence and amount of mineralized products. POF is characterized by a low-grade neoplastic proliferation of fibroblastic connective tissue of variable cellularity in which a variety of bone, osteoid, dentinoid (dentin-like) or even cementum-like material is present. Definitive treatment typically requires en bloc resection of the mass and underlying bone, and is considered curative if excised completely.  

Many of the tumors previously described as fibromatous and ossifying epulides have been reclassified as peripheral odontogenic fibroma (POF). Peripheral odontogenic fibroma is a slow growing, benign neoplasm, common in the dog and uncommon in the cat. The surface epithelium appears normal, and radiographic features vary according to the presence and amount of mineralized products. POF is characterized by a low-grade neoplastic proliferation of fibroblastic connective tissue of variable cellularity in which a variety of bone, osteoid, dentinoid (dentin-like) or even cementum-like material is present. Definitive treatment typically requires en bloc resection of the mass and underlying bone, and is considered curative if excised completely.  

Reactive lesions are non-neoplastic gingival enlargements that are commonly grouped under the previously noted nondescript classification of epulides. The term ‘epulis’ (singular) has no specific histopathologic connotation and is a clinical designation for any localized, exophytic swelling on the gingiva. Reactive lesions include focal fibrous hyperplasia, pyogenic granuloma, peripheral giant cell granuloma and reactive exostosis. Marginal excision of these lesions, without inclusion of adjacent normal tissue, is generally sufficient, as local recurrence is uncommon.  

Reactive lesions are non-neoplastic gingival enlargements that are commonly grouped under the previously noted nondescript classification of epulides. The term ‘epulis’ (singular) has no specific histopathologic connotation and is a clinical designation for any localized, exophytic swelling on the gingiva. Reactive lesions include focal fibrous hyperplasia, pyogenic granuloma, peripheral giant cell granuloma and reactive exostosis. Marginal excision of these lesions, without inclusion of adjacent normal tissue, is generally sufficient, as local recurrence is uncommon.  

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