Odontogenic Tumors Lecture PDF

Oral & Maxillofacial Surgery Lecture College of Dentistry/ University of Baghdad 5th year Dr. Auday M. Al-Anee Odontogenic tumors INTRODUCTION Odontogenic tumors are pathologic outcomes from tissue elemen...

Oral & Maxillofacial Surgery Lecture College of Dentistry/ University of Baghdad 5th year Dr. Auday M. Al-Anee Odontogenic tumors INTRODUCTION Odontogenic tumors are pathologic outcomes from tissue elements that are part of the tooth-forming apparatus, that is, odontogenic tissues. These tumors occur exclusively in the bones of the jaw particularly around the teeth-bearing segments. Patients with odontogenic tumors usually present with symptomatic or asymptomatic swelling in the oral and maxillofacial region. Most of these swellings have either tooth-associated symptoms or tooth-associated radiological changes. The general dentist possesses a unique opportunity to be the first health care professional to see anatomic or radiographic changes in the maxillofacial region due to proximity of the neighboring structures that they routinely treat. Because general dentists serve as the preliminary point of patient contact and see patients on a regular basis, it is imperative that they become familiar with the recognition and diagnosis of odontogenic tumors. Odontogenic tumors comprise neoplastic growths of benign, malignant, or tumor- like malformations originating from odontogenic tissues. The interactions between ectodermal and mesenchymal elements from odontogenic tissues can initiate tumor formation due to disturbance in signaling mechanism for their growth and proliferation. The World Health Organization (WHO) has a classification system for odontogenic and maxillofacial bone tumors (5th edition, 2022) which is: Benign epithelial odontogenic tumours  Adenomatoid odontogenic tumour  Squamous odontogenic tumour  Calcifying epithelial odontogenic tumour  Ameloblastoma, extraosseous/peripheral  Ameloblastoma, unicystic  Ameloblastoma, conventional  Adenoid ameloblastoma 1 Oral & Maxillofacial Surgery Lecture College of Dentistry/ University of Baghdad 5th year Dr. Auday M. Al-Anee  Metastasizing ameloblastoma Benign mesenchymal odontogenic tumours  Odontogenic fibroma  Odontogenic myxoma  Cementoblastoma  Cemento-ossifying fibroma. Benign mixed epithelial and mesenchymal odontogenic tumours  Ameloblastic fibroma  Primordial odontogenic tumour  Odontoma - Odontoma, compound type - Odontoma, complex type  Dentinogenic ghost cell tumour. Clinical Considerations Odontogenic tumors, as a group, are relatively uncommon; several are rare, and a few are very rare. The clinical importance of odontogenic tumors is not measured by their numbers, but because some lesions are very destructive and surgical management involves the face, oral tissues, and jaws of both young and old patients. Correlation of clinical, radiographic, and histologic analyses is necessary to prevent over- or under-treatment. There are no clinical signs, symptoms, or physical findings that permit diagnosis of specific odontogenic tumors. The age and sex of the patient and location characteristic of lesions are derived from pooled data compiled from the literature and unpublished cases. Such information is useful only when combined with other diagnostic features. Imaging Because most odontogenic tumors emanate from or involve the jaws, imaging modalities, including plain radiography (periapical, occlusal, panoramic), computed tomography (CT), CT three-dimensional (3D) reconstruction, computer- 2 Oral & Maxillofacial Surgery Lecture College of Dentistry/ University of Baghdad 5th year Dr. Auday M. Al-Anee generated models, magnetic resonance imaging (MRI), and positron emission tomography (PET) scan CT, offer an unparalleled opportunity to view the tumor in relation to the jaws and adjacent soft tissues. Radiographic images do not provide pathognomonic identification of odontogenic lesions, because several odontogenic tumors as well as nonodontogenic lesions may share imaging characteristics. However, highly useful visual information can be gathered to study a lesion for presumptive differential diagnoses, selection of biopsy sites, and management decisions. A lesion’s position, size, and shape; presence or absence of lesional calcifications; estimation of soft tissue volume in relation to calcified tissue, cyst formation, and impingement on or inclusion of vital anatomic structures; displacement of teeth or root resorption; and interface boundaries between lesion and host bone help the clinician to form a characterization of the tumor’s activity and aggressiveness. Odontogenic tumors are most often discovered by dental radiography (periapical, occlusal, or panoramic) as part of routine screening during a dental visit, examination of a patient with a specific complaint (e.g., pain or oral soft tissue or facial enlargement), or elective consultation (e.g., orthodontic or orthognathic surgery). The judgment of the clinician will determine the extent and types of imaging that are needed or most useful for the management of a specific case. Yet, in many instances, there is a tendency to use fewer imaging modalities than are desirable—which is usually later regretted, as imaging provides a valuable documentary and study tool. Overall viewing of bone and soft tissue by consecutive anatomic ―slices‖ and planes is provided by CT and MRI, respectively. The volume of the tumor and the interface margins between the tumor and surrounding bone and soft tissue is roughly revealed by PET-CT, obtained after injection of a glucose isotope conjugate metabolized by the tumor. The 3D CT (three-dimensional computerized tomogram) permits viewing the lesion in almost kaleidoscopic anatomic displays; the 3D CT generated model provides an excellent physical reproduction of the anatomic part and tumor. The model is useful for planning or carrying out a mock surgical procedure and provides a mechanical frame on which to contour a reconstruction appliance. 3 Oral & Maxillofacial Surgery Lecture College of Dentistry/ University of Baghdad 5th year Dr. Auday M. Al-Anee Diagnostic considerations (Biopsy) Definitive diagnosis is established only after incisional, excisional, or intraoperative frozen section biopsy for histologic analysis. The specific biopsy technique is selected after careful assessment of the patient (age, physical health, and emotional status) and of the use of local, sedation, or general anesthesia to ensure patient cooperation, gain access to the lesion, and obtain sufficient tissue for study. An incisional biopsy performed several weeks before definitive management often precludes excision or frozen section diagnostic ―surprises.‖ Thus, time is gained to receive a soft or calcified tissue diagnosis, plan the surgical procedure, prepare and/ or obtain special presurgical requirements, and fully discuss management with the patient or guardian. Excisional biopsy should be performed for completely calcified odontogenic lesions (i.e., malformations radiographically demonstrating only teeth or a cementum-like tissue) in which histologic diagnosis is not immediately essential; for physically impaired patients for whom several anesthetic or surgical exposures should be avoided; or for small lesions (approximately 1.0 to 1.5 cm in diameter) that can be excised completely and can reasonably be expected not to require further operation after histologic study. Intraoperative frozen section should be used to study questionable soft tissue encountered in areas not sampled by the incisional biopsy, and to examine the adequacy of the boundary between lesion and host bone and/or soft tissue in instances in which extensive resection is not planned. The preparation of a good frozen section is technique-sensitive and requires proper specimen orientation and avoidance of incorporated dense bone (which nicks the microtome blade and disrupts the tissue section). Management The objectives of the surgical management of odontogenic tumors are the eradication of the lesion, preservation of normal tissue to the extent possible, and restoration of significant tissue loss, form, and function. All agree that the surgical procedure should be sufficient to the need; however, in many instances there is 4 Oral & Maxillofacial Surgery Lecture College of Dentistry/ University of Baghdad 5th year Dr. Auday M. Al-Anee disagreement among surgeons and pathologists about the extent of surgery that specific tumors require. Some surgeons maintain an almost mystical adherence to a conservative surgical approach, in the conviction that all odontogenic tumors are benign. This viewpoint amounts to a planned recurrence for some lesions. The basis for this opinion is the belief that a recurrence or recurrences (more properly, regrowth of residual lesion) can be managed by a simpler procedure that can avoid jaw resection. However, one of the results of such an approach is the creation of a shotgun pattern of recurrence by which the lesion is spread throughout a larger area, thus compounding the surgical problem. Other surgeons are routinely aggressive in their approach to all odontogenic tumors, and so sacrifice more normal tissue than is necessary to ablate the lesion. The argument has been made that a well-planned and executed resection and reconstruction serves the patient physically and emotionally better than repeated surgical procedures. All excisions involving bone can best be described by the following designations: enucleation, curettage, marsupialization, recontouring, resection without continuity defect, resection with continuity defect, and disarticulation. Enucleation means completely separating the lesion from the adjacent bone and removing it. Curettage involves raking out the lesion together with part of the adjacent bone (generally, 1-2 mm) using mechanical, physical, and chemical materials. Marsupialization is the surgical technique of cutting a slit into an abscess or cyst and suturing the edges of the slit to form a continuous surface from the exterior surface to the interior surface of the cyst or abscess. Sutured in this fashion, the site remains open and can drain freely. Disarticulation resections are rarely required variants of segmental resection of the mandible, and they are required by a variety of pathologic processes of the jaws and contiguous structures, when they extend into the condylar region, thereby requiring its sacrifice. Certainly at present, there are no absolute standards of management for many odontogenic tumors and the treatment of several lesions continues to be debatable. 5 Oral & Maxillofacial Surgery Lecture College of Dentistry/ University of Baghdad 5th year Dr. Auday M. Al-Anee Odontoma Odontoma is a benign tumor of mixed odontogenic origins consisting of both odontogenic hard and soft tissue. It is thought to be the most frequently encountered odontogenic tumor. Odontomas are composed of both epithelial and ectomesenchymal components that contribute to enamel- and dentin-like structures within the lesion. Although odontomas may consist of normal-appearing enamel/dentin structures, they have defects in their structural arrangement and hence they are considered as hamartomas, or tumor-like malformations, rather than true neoplasms. The odontoma is seen predominantly in the second and third decade of life and has a slight female predilection. There are 2 main types: compound and complex. The lesion is easily recognized in radiographic examinations and appears as a radiopaque mass with thin radiolucent rim. Odontomas are usually managed by conservative enucleation but more extensive surgical procedures may be necessary for larger, more extensive lesions. Clinical features Odontomas are slow-growing, expanding, and painless intrabony lesions. Pain and inflammation may, however, result from secondary infection. The 2 types of odontomas are complex and compound odontoma. The distinction between these 2 types is based on either the appearance of tooth-like structures or disorganized mass of dental tissue. The complex type is unrecognizable as dental structures, appearing as a radiopaque mass with varying densities. The compound odontoma has recognizable enamel, dentin, and cementum and consists of individual recognizable small teeth. The complex odontomas are located in the posterior mandible and identified based on disorganized mass of dental tissues, that is, enamel and/or dentine. Compound odontomas are located in the anterior maxillae and identified based on well-organized, multiple tooth-like structures. Odontomas can also be associated with other odontogenic tumors such as calcifying odontogenic cyst, ameloblastic fibroodontoma (AFO), and odontogenic fibromas. The association of odontoma with Gardner syndrome and coronoid hypoplasia has also been reported. 6 Oral & Maxillofacial Surgery Lecture College of Dentistry/ University of Baghdad 5th year Dr. Auday M. Al-Anee Diagnostic modalities In most cases odontomas can be diagnosed based on their radiographic appearance alone. The radiologic appearance depends on the stage of the lesion. The first stage is characterized by a radiolucent appearance due to lack of calcification. Partial calcification or radiopacity are seen in second or intermediate stage. The third stage is characterized by predominance of radiopaque masses of dental hard tissues with a thin radiolucent zone. Resorption of adjacent tooth or roots are uncommon. Association with unerupted teeth may be seen. Radiographically compound odontomas seem as collection of multiple tooth-like structures of varying size and shape with periphery of narrow radiolucent zone, whereas complex odontomas seem as calcified mass with radiodensity of tooth structures with periphery of narrow radiolucent zone. Microscopically odontomas are observed with multiple mineralized structures resembling small, single-rooted teeth with loose fibrous matrix. Pulp tissue may be seen in coronal and radicular zone of toothlike structures. Differential diagnosis Differential diagnosis may include supernumerary tooth, AFO, and osteomas. Based on formation and the number of toothlike structures present, a supernumerary tooth can be easily differentiated from odontomas. Distinguishing AFO from odontoma can be challenging. Radiographically, the radiopacity seen in AFO is usually scattered, whereas the odontomas will have a central area of radiopacity. Radiographic appearance of complex odontoma may be confused with osteoma due to mineralized mass of tissue. However, the radiolucent zone at the periphery of the odontoma, which represents the dental follicle along with the radiodensity of the mass having a density similar to teeth, will differentiate odontomas from osteomas. Management Odontomas are managed with conservative surgical excision and special surgical considerations are given for large odontomas. The prognosis of the condition is usually excellent with minimal to no recurrence. 7 Oral & Maxillofacial Surgery Lecture College of Dentistry/ University of Baghdad 5th year Dr. Auday M. Al-Anee Ameloblastoma Ameloblastomas are the second most common benign odontogenic tumor. They are potentially aggressive, locally invasive, slow-growing benign tumors that may originate from cell rests of dental lamina, epithelium from the enamel organ, epithelial lining of odontogenic cyst (ie, dentigerous cyst), and basal cell layer of oral mucosa. Based on clinical, radiologic, histologic, and prognosis aspects, ameloblastomas are classified as (1) conventional (classic)/solid/multicystic ameloblastomas, (2) unicystic type, (3) peripheral,and (4) desmoplastic ameloblastoma. Histopathologic examination is mandatory for confirmation of diagnosis. Ameloblastomas are managed by wide surgical resection, and recurrences have been reported. Clinical features Ameloblastomas are uncommon among children and is predominantly seen in third and fourth decades of life with a male predilection. The mandible is the favored site over the maxilla by about a 4.5:1 ratio. The posterior mandible is the most commonly affected site (70% found in angle of mandible). The ameloblastoma is asymptomatic and remains undiscovered until lesional growth produces intraoral and/or external jaw swelling, tooth and dental occlusion disturbances, or incidental radiographic examination reveals a lesion. Paresthesia is an uncommon symptom and pain is rarely a presenting symptom unless the lesion causes root resorption and/or tooth mobility. The clinical signs such as pain and disfigurement may be seen as the lesion advances in the size. The pain occurs due to pressure effects from the mass size on peripheral nerves and secondary infection. Ameloblastomas that present with large expansile mass of the jaw can cause thinning of cortical plate, and crepitation or egg shell crackling may be elicited while palpating jaw. Rarely the lesion can perforate jaw bone leading to ulcerated growth in oral cavity and sometimes the skin. Peripheral ameloblastomas present as painless, slow- growing gingival swelling that may produce shallow depression in the underlying bone rather than infiltration. 8 Oral & Maxillofacial Surgery Lecture College of Dentistry/ University of Baghdad 5th year Dr. Auday M. Al-Anee Diagnostic modalities Radiographic examination can greatly assist in the diagnosis of ameloblastomas. The frequent presentation type of ameloblastoma is solid/multicystic type, which appears as multilocular radiolucent destruction of bone. A well-defined, small or large radiolucent area in the bone gives the appearance of honeycomb or soap bubble appearance. The destructive changes of the jaw bone may be either confined to alveolar bone or half the mandible. Buccal and lingual cortical plate expansions are observed. Cortical plate expansions can be well recognized in occlusal radiographs. Resorption of adjacent roots of teeth is frequently observed. Association of unerupted tooth is common and adds a layer of complexity in differentiating ameloblastoma with circumferential type of dentigerous cyst. Although ameloblastoma frequently shows irregular scalloping border, this is not a consistent finding in all the cases. Mixed radiographic appearance is due to osseous septa in the lesion but not a true mineralized content in the lesion. Unicystic ameloblastoma shows a large unilocular radiolucent destruction of the involved jaw bone. Microscopic examination shows ameloblast-like cells and stellate reticulum–like cells with fibrous stroma. Histologic variants of ameloblastomas include follicular, plexiform, acanthomatous, granular cell, desmoplastic, clear cell, basal cell, keratoameloblastoma, papilliferous type, mucous cell, hemangiomatous, and extragnathic types. (Several microscopic subtypes – do not affect prognosis). Differential diagnosis Differential diagnosis of ameloblastoma can be categorized into radiolucency with and without mineralization changes. Differential diagnosis of uni-/multilocular radiolucency without mineralization includes odontogenic keratocyst, central giant cell granuloma, and dentigerous cyst, whereas differential diagnosis panel of uni- /multilocular radiolucency with mineralization includes odontogenic myxoma, calcifying odontogenic cyst, and calcifying epithelial odontogenic tumor. One must look for size, location, and presence/absence of mineralization while formulating differential diagnosis. Central giant cell granulomas are commonly reported in anterior mandible, whereas ameloblastomas are seen in posterior region. Odontogenic keratocyst has a tendency to expand in anteroposterior region, 9 Oral & Maxillofacial Surgery Lecture College of Dentistry/ University of Baghdad 5th year Dr. Auday M. Al-Anee whereas ameloblastomas tend to expand in a buccal-lingual direction. Dentigerous cyst tends to show pericoronal radiolucency, whereas ameloblastomas show impacted tooth in the lesion, not necessarily pericoronal radiolucency. Mineralization density is greatly appreciated in calcifying epithelial odontogenic tumor and calcifying odontogenic cyst. Unicystic Ameloblastoma A unicystic ameloblastoma may form de novo or develop secondarily in an odontogenic keratocyst or dentigerous cyst. These have the best prognosis, and a lower recurrence rate.The lesion may remain small, become large, or even develop into a multicystic form. Small or large unicystic lesions that contain unerupted (impacted) teeth, or those without unerupted teeth, are usually identified radiographically as a dentigerous cyst or odontogenic keratocyst. However, an often-overlooked radiologic feature of unicystic ameloblastoma involving a dentate area is the partial resorption of tooth roots (permanent or deciduous), a rare occurrence in dentigerous or odontogenic keratocyst. The unicystic ameloblastoma exhibits two other notable clinical differences from the multicystic, solid, and peripheral forms, besides its physical shape. First, the lesion usually occurs in adolescents, teenagers, and young adults; and second, the lesion exhibits the previously described peripheral-encompassing connective tissue wall of varying thickness. Recognition of the proliferative pattern of the unicystic ameloblastoma has clinical importance. Growth within the cyst cavity (intraluminal), growth along the cavity surface (luminal), or proliferation into the connective tissue of the cyst wall (mural) a greatly affects treatment. Management of luminal or intraluminal subtype is usually enucleation, whereas mural subtypes are managed by resection with a 1.5cm margin. Curettage of the bone is discouraged because it may implant foci of ameloblastoma more deeply into bone. Adjunctive treatment of the bone tumor bed by chemical fixation with Carnoy solution is of theoretical but unproven value, and cryosurgery gives inconstant benefit, as well as risk of sequestration or pathologic fracture. 10 Oral & Maxillofacial Surgery Lecture College of Dentistry/ University of Baghdad 5th year Dr. Auday M. Al-Anee Conventional (Solid and Multicystic) Ameloblastomas These are the most common type. They are usually radiolucent on radiography and clinically are partially or completely solid. Management is resection with a 1.5cm margin. As both conventional Ameloblastoma and unicystic ameloblastoma have been found to harbor BRAFp.V600E mutations, aggressive and destructive tumours could be candidates for BRAF-targeted therapy that has the potential to reduce tumour size and ultimately enable a conservative surgical procedure. Preliminary data of biological treatment show effectiveness in selected cases. BRAF is a human gene that encodes the B-Raf protein, which is responsible for cell proliferation. When the BRAF gene is mutated, it is constantly activated. This leads to uncontrolled cell proliferation (independent of any external stimulus), a condition that may result in the generation of tumors. Somatic oncogenic mutations in the BRAF gene (specifically the BRAF-V600E mutation) occur in more than 60% of mandibular ameloblastomas. This is a big breakthrough, which is a genetically based patient specific treatment, to ameloblastoma. In the cases treated, the BRAF inhibitor resulted in substantial tumor regression, allowing for non-mutilating complete surgical removal, bone regeneration and organ preservation. Peripheral /ExtraosseousAmeloblastoma These have a good prognosis, arise from the gingivae rather than tooth and are most common in premolar area of mandible, then tuberosity of the maxilla. A radiograph should be taken to exclude a perforating intraosseous ameloblastoma. Management is conservative excision. Long term follow is required. Malignant (Metastasising) Ameloblastoma and Ameloblastic Carcinoma Ameloblastoma sometimes exhibit behavior of metastases that are most often found in the lungs. The diagnosis of malignant ameloblastoma should be made when a tumor in both primary and metastatic locations demonstrate histopathologic features of ameloblastoma. If surgically feasible, wide resection and reconstruction should be performed on the primary and metastatic lesions by a surgical team. 11 Oral & Maxillofacial Surgery Lecture College of Dentistry/ University of Baghdad 5th year Dr. Auday M. Al-Anee Radiation and chemotherapy are questionable modalities for adjunctive treatment and should be reserved for palliation. The diagnosis of ameloblastic carcinoma should be made when microscopic examination of ameloblastoma cases shows cytologic features of malignancy in the primary tumor. Ameloblastic carcinomas show local aggressive behavior but do not demonstrate the character of metastasis. 12 L\ L\ Oral & Maxillofacial Surgery Lecture College of Dentistry/ University of Baghdad 5s year Dr. Auday M. Al-Anee Non- odontogenic tumors Important points * Nonodontogenic tumors of the jaws are common in the pediatric population; these tumors include giant cell lesions, fibro-osseous lesions, and desmoplastic fibroma. * Giant cell lesions of the maxillofacial skeleton range clinicatly from slowly growing, asymptomatic radiolucency discovered on routine radiographs to rapidly expanding, aggressive tumors characterized by pain, root resorption, and a high recurrence rate. * Fibro-osseous lesions represent a group of benign conditions that are characterizedby replacement of normal bone with fibrous connective tissue that gradually undergoes mineralization. * Desmoplastic fibroma is recognized as a benign bony neoplasm and as the intraosseous counterpart of soft tissue fibromatosis. Giant cell lesions Giant cell lesions of the maxillofacial skeleton range clinically from slowly growing, asymptomatic radiolucency discovered on routine radiographs to rapidly expanding, aggressive tumors characterized by pain, root resorption, and a high recurrence rate. They are generally considered to be nonneoplastic, although some lesions tend to behave aggressively like a neoplasm. Names such as central giant cell granuloma, giant cell lesion, giant cell tumor, or giant cell reparative granuloma have added to the complexity and confusion of this lesion. The reparative term has been rejected in recent times because the lesions are typically destructive and aggressive, never reparative. The term granuloma is also a misnomer; however, the central giant cell granuloma has now become synonymous with a lesion in the maxillofacial skeleton. Central giant cell granuloma (CGCG) was first described by Jaffe in 1953 as a reparative granuloma to convey that it was not a neoplasm. The central giant cell lesion is a benign localized proliferation that is osteolytic and sometimes aggressive, consisting of fibrous tissue containing multinucleated giant cells, 1 Oral & Maxillofacial Surgery Lecture College of Dentistry/ University of Baghdad sth year Dr. Auday M. Al-Anee hemorrhagic areas, and deposits of hemosiderin, and occ€rsionally involving a bone reaction. Clinical Findings These lesions occur in all ages; however, they are seen predominantly in children and young adults and are usually diagnosed before 30 years of age. Female patients are affected more often than male patients, and some studies have shown arate of about 60%nwomen. The mandible is affected more often than the maxilla. The premolar and molar regions of the mandible are more affected than the ascending ramus region, and, rarely, there is involvement of the mandibular condyle or the maxillary sinus. In most cases it presents as an asymptomatic lesion detected on routine radiographic examination; however, pain, paresthesia, perforation of cortical bone, mobility, and loss of teeth are reported in aggressive lesions. Demographics: * Predilection for women * Occurrence in the first 3 decades of life * Mandible more than maxilla, most often anterior to the first molar * Most often a solitary lesion Physical examination:. Asymptomatic, but can be associated with discomfort, pain, paresthesia o Teeth can be displaced or nonvital o Maxillary lesions may present as nasal obstruction or epista