W21 BDS10008 Odontogenic Tumors PDF

BDS10008 Odontogenic Tumors (1) Date : //2021 Aims: The aim of this lecture is todetail the histopathological classification of odontogenic tumors of the jaws and the principle clinical, radiological and histopathological features of ameloblastoma. Objectives: On completion of this lecture, the stud...

BDS10008 Odontogenic Tumors (1) Date : //2021 Aims: The aim of this lecture is todetail the histopathological classification of odontogenic tumors of the jaws and the principle clinical, radiological and histopathological features of ameloblastoma. Objectives: On completion of this lecture, the student should be able to: Understand the histopathological classification or odontogenic tumors of the jaws Understand the principle radiological and histopathological features of ameloblastoma  They arise from tooth forming apparatus (odontogenic epithelium & mesenchyme) and their remnants  Are group of lesions of diverse histopathologic types and clinical behavior  They are found exclusively in the mandible and maxilla (and occasionally gingiva).  The etiology and pathogenesis of this group of lesions are unknown. Odontogenic tumors Epithelial Composed of odontogenic epithelium only Mesenchymal Composed of odontogenic ectomesenchyme only [dental papilla-dental follicle] Benign [ameloblastoma is the most common] Benign Odontogenic carcinomas Odontogenic sarcomas Mixed Composed of both odontogenic epithelium & ectomesenchyme Benign [odontoma is the most common] Odontogenic carcinosarcomas Ameloblastoma It is a benign epithelial intraosseous progressively growing characterized by expansion and tendency for local recurrence if not adequately removed [locally aggressive]. It is the most common, odontogenic tumor excluding odontomas. Origin (histogenesis) They may arise from: Dental lamina or its remnants. Enamel organ or its remnants. Epithelial lining of an odontogenic cyst. Basal cells of the oral mucosa. Ameloblastoma Types Conventional or classical or intraosseous Ameloblastoma [Most common] Unicystic ameloblastoma Peripheral (extraosseus) Ameloblastoma Metastasizing ameloblastoma Ameloblastoma Clinical features Mandible is mostly affected (80%) especially posterior area followed by anterior mandible, posterior maxilla and anterior maxilla It appears as a painless slowly growing swelling or expansion of jaw bone which can later exhibit accelerated growth With increasing size, some complications may occur including: loosening of teeth, pain, paraesthesia, soft tissue invasion, facial deformity Ameloblastoma Radiographic features  Multilocular radiolucency is described as (honeycomb or soap - bubble appearance). Less commonly unilocular  Buccal & expansion  Resorption of adjacent teeth lingual the cortical roots  Unerupted tooth may be seen of Ameloblastoma Radiographic features Ameloblastoma Macroscopic features Most tumors have combinations of cystic & solid features Ameloblastoma Histopathological features 1- Follicular pattern 2- plexiform pattern N.B. The difference in histopathologic features has no clinical significance. Ameloblastoma Histopathological features A- Follicular pattern  Discrete islands of odontogenic epithelium (resemble enamel organ epithelium) in mature connective tissue stroma  The epithelial masses consist of a central mass of loosely arranged angular cells (stellate reticulumlike) surrounded by tall columnar cells (ameloblast like cells), their nuclei are away from basement membrane (reversed polarity). Ameloblastoma Histopathological features A- Follicular pattern  Occasionally, there is a distinctive zone of hyalinization surrounding the epithelial islands. It is termed juxta-epithelial hyalinization. Histopathological features A- Follicular pattern 1. Cystic: stellate reticulum like cells often undergo cystic change which will produce microcyst. The microcyst unite to form larger macrocystic spaces surrounded by flat cells. Histopathological features A- Follicular pattern 2- Acanthomatous pattern Occurs due to squamous metaplasia of the inner cells within the follicle with keratin formation. Histopathological features A- Follicular pattern 3- Granular pattern transformation of group of central cells to granular cells, which are filled with eosinophilic granules that resembles lysosomes ultrastructurally & histochemically Nucleus is pushed against the cell membrane. Histopathological features A- Follicular pattern 4- Basal cell pattern  Composed of nests of uniform basaloid cells, very similar to basal cell carcinoma of skin  No stellate reticulum is present in the central portions of the nests. Basal cell carcinoma Histopathological features A- Follicular pattern 5-Desmoplastic Ameloblastoma  Characterized by small islands and cords of odontogenic epithelium in densely collagenized stroma [Due to increased production of the cytokine known as transforming growth factor B (TGF-B) suggesting that it may be responsible for the desmoplasia] Ameloblastoma Histopathological features B- Plexiform pattern Consists of long anastomosing cords of odontogenic epithelium in connective tissue stroma Cysts formation occurs within the connective tissue stroma.occurs by stromal breakdown Cystic Acanthomatus Follicular Histopathology of ameloblastoma Granular Basal Plexiform Desmoplastic Ameloblastoma Treatment Wide surgical excision including an area of bone beyond the apparent radiographic margin (surgical removal with safety margin)  Because ameloblastoma tends to infiltrate between intact cancellous bone trabeculae before bone resorption become radigraphically evident so the actual margin of the tumor usually extends beyond the apparent radiographic margin Ameloblastoma Prognosis   It has a high recurrence rate. Follow up should be at least 25 years, but lifelong follow up should be considered Unicystic Ameloblastoma Definition: It is a variant of intraosseous ameloblastoma that occurs as a single cystic cavity, with or without luminal proliferation It accounts for 5-22% of all ameloblastomas Clinical features  Usually diagnosed in 2nd decade  Mandible posterior region is the most common site  Asymptomatic, painless jaw expansion Unicystic Ameloblastoma Radiographic features Appears as a well defined unilocular radiolucency Often associated with an unerupted tooth Unicystic Ameloblastoma 3 histopathologic variants 3 histopathologic variants 1-Luminal A cyst wall lined totally or partially by ameloblastic epithelium  Basal cells columnar with their nuclei hyperchromatic & reverse polarized  The overlying epithelial cells consist of stellate reticulum like cells. 3 histopathologic variants 2- intraLuminal One or more nodule of ameloblastoma (mostly plexiform pattern) project from lining into cyst lumen 3- Mural The fibrous wall of cyst is infiltrated with typical follicular or plexiform ameloblastoma Unicystic Ameloblastoma Treatment Unicystic ameloblastoma is usually treated by enucleation except mural type should be treated as a conventional AB: marginal resection (surgical removal with safety margin) Extraosseous Peripheral Ameloblastoma Definition It is a benign tumor that occur in the soft tissue of gingiva or edentulous alveolar areas, showing microscopic features of ameloblastoma Clinical features painless, sessile, exophytic mass with smooth or papillary surface. most commonly found on the posterior gingival and alveolar mucosa. Radiographic features: Negative in x-ray, may cause superficial erosion of bone (cupping or saucerization) Extraosseous Peripheral Ameloblastoma Histopathologic features All histopathologic features of intraosseous ameloblastoma can be encountered Treatment & Prognosis Conservative surgical excision [It has lower recurrence rate than conventional ameloblastoma]. Malignant ameloblastomas Metastasizing ameloblastoma Ameloblastic carcinoma Metastasizing Ameloblastoma Definition It is an ameloblastoma that metastasizes despite its benign histopathological appearance  it is a rare malignant ameloblastoma It is identified by clinical behavior rather than its histopathology Clinical features Primary site is the mandible followed by maxilla. Metastatic deposits are most commonly seen in lungs, followed by lymph nodes and bone [usually there is long latent period before metastasis]  Some cases occur after repeated surgical interventions Metastasizing Ameloblastoma Histopathologic features For this diagnosis to be made, both primary& metastatic lesions must have histological features of benign ameloblastoma No specific metastasis features predict If signs of dysplasia are seen the lesion is diagnosed as ameloblastic carcinoma Ameloblastic Carcinoma Definition It is a rare primary epithelial odontogenic malignant neoplasm It is the malignant counterpart of ameloblastoma Ameloblastic carcinoma has cytologic features of malignancy (signs of dysplasia) in primary tumor & metastatic deposits Ameloblastic Carcinoma Radiographic features show poorly defined radiolucency consistent with malignancy Cortical expansion, perforation and infiltration into adjacent structures Primary intraosseous carcinoma (NOS) Definition It is a central carcinoma that can’t be categorized as any other type of carcinoma It arises from odontogenic epithelium or in odontogenic cysts [radicular/residual cysts are the most common precursors followed by dentigerous cysts and odontogenic keratocysts] Metastatic carcinoma must be excluded Primary intraosseous carcinoma (NOS) Definition It is a central carcinoma that can’t be categorized as any other type of carcinoma It arises from odontogenic epithelium or in odontogenic cysts [radicular/residual cysts are the most common precursors followed by dentigerous cysts and odontogenic keratocysts] Metastatic carcinoma must be excluded Key points Ameloblastoma is the most common, odontogenic tumor excluding odontomas. It has locally aggressive behavior, that’s why, it requires surgical removal with safety margin and long term follow up (due to its high recurrence rate).  The different histopathologic patterns of ameloblastoma exhibit no clinical significance. Luminal and intraluminal unicystic ameloblastoma as well as extraosseous peripheral ameloblastoma have more favorable prognosis than conventional ameloblastoma and usually treated by enucleation Aims: The aim of this lecture is todetail the histopathological classification of odontogenic tumors of the jaws and the principle clinical, radiological and histopathological features of ameloblastoma. Objectives: On completion of this lecture, the student should be able to: Understand the histopathological classification or odontogenic tumors of the jaws Understand the principle radiological and histopathological features of ameloblastoma Reading material: Students are advised to review any relevant teaching provided in the first year. In addition they are advised to read relevant sections of the following texts: Robinson M et al. Soames’ and Southam’s Oral Pathology. 5th edition. Oxford University Press, 2018 pp 149-159 Odell E.W. Cawson’s Essentials of Oral Pathology and Oral Medicine. 9th Edition. Elsevier, 2017 pp 165-179 Thank you