Odontogenic Tumors Handout PDF

Odontogenic tumors  Odontogenic tumors Odontogenic tumors originate from : 1- the epithelial parts of the odontogenic apparatus, basal lamina epithelial rests of Serre's , reduced enamel epithelium ,epithelial root sheath of Hertwig or its remnants (epithelial rests of...

Odontogenic tumors  Odontogenic tumors Odontogenic tumors originate from : 1- the epithelial parts of the odontogenic apparatus, basal lamina epithelial rests of Serre's , reduced enamel epithelium ,epithelial root sheath of Hertwig or its remnants (epithelial rests of Mallassez). 2- They may arise from the mesenchymal parts of the odontogenic apparatus, dental sac or dental papilla. 3- They also may originate from both epithelial and mesenchymal parts. Classification: Odontogenic tumors are classified according to the cell of origin into: I- Epithelial Odontogenic Tumors 1- Simple Ameloblastoma 2- Adenomatoid Odontogenic Tumor 3- Calcifying Epithelial Odontogenic Tumor II- Connective Tissue Odontogenic Tumors 1- Odontogenic Fibroma 2- Odontogenic Myxoma 1 3- Cementomas a) Cementoblastoma b) Periapical Cemental Dysplasia c) Gigantiform Cementoma 4- Dentinoma III- Mixed Odontogenic Tumours 1- Ameloblastic fibroma 2- Ameloblastic fibro-dontome 3- Odontoma: Complex and compound. Epithelial Odontogenic Tumours Simple Ameloblastoma Def.: Ameloblstoma is a locally aggressive, benign epithelial neoplasm of odontogenic origin, Ameloblastoma constitutes 1% of oral neoplasms. Histogenesis: An ameloblastoma can arise from: (1 ) Remnants of the dental lamina (rests of Serres), (2) Reduced enamel epithelium, (3 ) Rests of Malassez. 2 Clinically: Age: Mostly between 20 to 40 years Sex: No sex predilection. Race: More frequent in Africans than in white. Site: commonly in the mandible, molar Ameloblstoma may occur centrally (intra bony ) or peripherally , the peripheral lesions are less aggressive than the central ones. Appearance: The tumor is slowly growing, locally aggressive, tends to expand the bony cortices , producing a thin shell of bone causing large facial deformities. This thinned outer shell of bone cracks easily when palpated – a diagnostic sign referred to as “eggshell cracking.” Ameloblastomas have a high recurrence rate if they are not widely and carefully excised. Radiographically Unilocular or Multilocular, irregular radiolucent area that gives the radiograph a “soap bubble” or "Honey comb" appearance.. 3  Multilocular radiolucency in the mandible Histopathologically: The classic microscopic appearance of an ameloblastoma consists of epithelium similar to that of the epithelium forming the enamel organ of a normal tooth. Two main histological patterns are commonly described, follicular and plexiform patterns. The follicular pattern consists of epithelium in the form of islands, in a background stroma of non-neoplastic fibrous connective tissue. 4 The epithelial arrangements have an outer border composed of the palisaded, tall columnar ameloblast-like cells; the remainder consists of loosely arranged stellate reticulum-like cells This is called A- "Solid ameloblastoma". In some islands the stellate-like cells of the central area degenerate, forming central "Microcysts". Multiple microcysts appear in the same follicle and coalease together and form large cyst "Macrocyst". B- Cystic follicular Ameloblastoma The central cells of some follicles are transformed, through metaplasia, to squamous cells and may produce keratin in the center. When this occurs the histologic variant is referred to as the C- "Acanthomatous pattern". The central cells of other follicles may appear swollen and densely packed with eosinophilic granules. This pattern has been termed the D- "Granular cell variant". Variants commonly coexist in the same lesion. 5 The plexiform pattern: consists of epithelium that proliferates in a mesh or a plexus arrangement. The general pattern consists of thin strands of epithelium that are in continuity. And also formed of tall columnar cells resembling ameloblasts enclosing stellate-reticulum like cells. This is termed "Solid Plexiform pattern" cyst-like areas are present in the surrounding connective tissue, and as the blood vessels are the last to degenerate it dilates till exceeding the elastic limits and rupture, extravasating the RBCs and this is termed "Hemorrhagic plexiform pattern". Plexiform Ameloblastoma Adenomatoid Odontogenic tumor (AOT) Def: Adenomatoid odontogenic tumor is a well-circumscribed, benign, epithelial odontogenic tumor. The lesion is biologically non-aggressive and requires conservative treatment 6 Histogenesis: most probably originates from the reduced enamel epithelium. Clinically: Age: The lesion occurs during the second decade of life, commonly in patients 14 to 15 years of age. Sex: Females more than males. Site: anterior part of the maxilla, usually around an impacted canine. Appearance: The common presentation is in a patient who exhibits an area of painless swelling over an unerupted tooth. Radiographically The radiographic appearance of AOT is usually as a unilocular lesion with well-corticated borders that contains a tooth. Most lesions are radiolucent, but some contain faint flecks of radiopacities. Lesions often surround the crown of an impacted tooth,. 7 Histopathologically AOT is formed of a large number of packed epithelial cells; the cells are round in shape or sometimes spindle. The epithelial cells may take the shape of tall columnar cells with basal nuclei; these cells are arranged in the form of bands, convoluted tubules or duct-like structures. An eosinophilic band is present at the periphery of the cells. The stroma is very scanty and the tumor is surrounded by a well- formed connective tissue capsule. Spherical calcifications are often scattered throughout the epithelium. The stroma may contain diffuse areas of hyaline material. 1- The epithelium has the form of: a- Sheets and strands of spindle cells. b- Duct like appearance c- Convoluted bands , between opposing rows of columnar cells there is an acidophilic material. 8  2- The connective tissue stroma (scanty ) 3- Varying amount of acidophilic, hyaline material. This hyaline material appears to be dysplastic dentine. 4- Very rarely calcification is sometimes seen (enamel matrix). 5- The tumor is usually surrounded by a well-formed connective tissue capsule. Calcifying Epithelial Odontogenic Tumor (CEOT) Pindborg tumor Def.: It is a locally aggressive, epithelial, odontogenic tumor. CEOT occurs as either a central (intraosseous) or peripheral (extraosseous) lesion. Histogenesis: It originates from the epithelial rests of the dental lamina and/or the reduced enamel epithelium that overlies the crowns of the teeth. Clinically: Age: the ages of 20 and 60 years,. Sex: No sex predilection. Site: Most lesions occur in in the mandible. the molar area Peripheral CEOT most commonly occurs in the anterior part of the mouth. Appearance: The tumor presents as a slowly enlarging painless mass. Peripheral CEOT presents as a superficial soft tissue of the gingiva. 9 Radiographically Small unilocular radiolucency with faint flecks of calcified structures (Radioopacities).. Intraosseous lesions may occur over unerupted and/or displaced teeth. Histopathology It composed of: 1- Masses or islands and sheets of polyhedral epithelial cells. The cells exhibit… pleomorphism , hyperchromatism, prominent nucleoli, eosinophilic cytoplasm 2- Areas of homogenous hyaline eosinophilic material are often found within and between the epithelial sheets. 3- Diffuse spherical calcifications. 10  Connective Tissue Odontogenic Tumors Odontogenic Fibroma Def.: Odontogenic fibroma is a peripheral or intraosseous (central) benign, fibroblastic odontogenic neoplasm derived from connective tissue of odontogenic origin, and containing varying amounts of inactive odontogenic epithelium. Histogenesis: the tumor is believed to arise from fibroblastic element of the tooth follicle. Clinically: The peripheral odontogenic fibroma : focal growths of the gingiva,. It may be of normal coloration or erythematous when ulceration occurs. While central odontogenic fibroma: asymptomatic, painless swellings commonly located in the mandible. Radiographically: The radiographic appearance of the central lesion is that of a unilocular and well circumscribed radiolucencent area. While the peripheral lesion is usually located in the gingival soft tissue, therefore, negative in x-ray. 11 Histopathologically: It is composed of: 1. Primitive cellular fibroblastic tissue. 2. Strands or islands of inactive odontogenic epithelium resembling epithelial rests. 3. Islands of osteoid or cement like tissue or calcifications may be scattered in the fibroblastic mass. Odontogenic Myxoma Def.: Odontogenic myxoma is an aggressive lesion derived from odontogenic connective tissue and consists of a mucoid ground substance with widely scattered undifferentiated spindle mesenchymal cells. Clinically: Age: Affects young persons. 12 Sex: Equal in both sexes. Site: mandible and maxilla. Maxillary (in all areas ) Mandibular molar/premolar Appearance: Most lesions are painless, slowly enlarging swellings that sometimes displace teeth. Myxoma of the jaws appears as a bony hard fusiform swelling usually in place of a missing tooth or an unerupted tooth. Growth may be rapid. complete removal is difficult and recurrences are common. Radiographically Large lesions are multilocular radiolucency with a “soap bubble” or “honeycomb” pattern. resemblings ameloblastoma, without a distinct demarcation., illdefined radiolucencies. Histopathology The tumors consist of: It consists of separated spindle or angular-shaped cells against a background of basophilic, mucoid, nonfibrillar ground substance. The lesion is not surrounded by a fibrous capsule. 13  Cementoblastoma Def.: Cementoblastoma is an uncommon, benign, well-circumscribed, true neoplasm of cementum-like tissue growing in continuity with the apical cemental layer of a molar or premolar that produces expansion of cortical plates. Clinically Age: It occurs in patients around the age of 19. Site: Mandibular molar/premolar area, with lesions attached to the apical third of one of the roots. Sex: Males more than females. The lesions is a true neoplasms, uniformly expanding both the buccal and lingual cortical plates. Cementoblastoma is painfull and the pain become worse by palpation. The related teeth are usually vital. Radiographically Lesions are completely radiolucent, or mixed radiolucent/radiopaque, or completely radiopaque. Radiopaque lesions exhibit a peripheral zone of radiolucency continuous with the normal periodontal ligament space of the tooth. 14 Histopathology The lesion is characterized by a deposition of unmineralized eosinophilic matrix rimmed by cementoblasts that are continuous with the normal cementum layer of one of the tooth roots.. Central zone become more mineralized until all lesion become mineralized. increased numbers of reversal lines,. The root of the involved normal tooth with the normal cemental layer.are attached ,to the neoplastic cemental tissue Periapical Cemental Dysplasia Def.: Developmental dysplastic disturbance of cementum. It is fibroblastic in its early stages, and later it contains increasing amounts of cementum-like tissue interspersed with woven bone. Site: commonly in the mandibular incisor region. It usually involves several teeth. Sex: Females more than males. Radiographically: Early lesions shows ill-defined radiolucent area, related to the apices of the teeth. 1- (osteolytic stage) Later radiopaque masses are revealed radiographically 2- (cementoblastic stage). 15 Then, excessive amount of calcified materials is deposited in the focal area and appears as a well defined radiopacity surrounded by a radiolucent band 3- (mature stage). Histopathologically: Mixture of rounded "cementicles" large cement-like masses and woven bone Gigantiform Cementoma Def.: A familial type of osseous, dysplastic disturbance of cementum. Age: Middle age. Sex: Females more common males. Site: Multiple, often bilateral and symmetrical lesions. It is an uncommon lesion appearing as a lobulated mass of dense, highly calcified, almost acellular cementum. It attains a large size and thus causes expansion of the jaw. Radiographically: Dense radioopaque masses often lobulated. Histopathologically: Large sheets of tissue closely resembling secondary cementum. Many empty lacunae, few vascular channels are observed 16  Dentinoma Dentinoma is a rare lesion found in young persons. The common site is the mandibular molar area and may be associated with an impacted tooth. It causes swelling, pain and may even perforation of the mucosa. Histologically it is composed entirely of dentin and the presence of dentinal tubules. Mixed Odontogenic Tumors Mixed odontogenic tumors are lesions that originate from both epithelial and connective tissue odontogenic elements. Ameloblastic Fibroma Def.: Ameloblastic fibroma is a benign, well-circumscribed mixed odontogenic lesion. The ameloblastic fibroma is a true histologic mixed tumor because the epithelial and mesenchymal components are part of the neoplastic process. Clinically Age: young patients with an average age of 14 years. Site: Commonly located in the mandibular molar area. 17 It is a slowly growing lesion, and causes slight buccal and lingual cortical expansion. Radiographically They are unilocular or multilocular radiolucent areas, resembling ameloblastoma. Histopathologically It consists of thin strands, and cords of odontogenic epithelium, they consists of a peripheral layer of cuboidal or columnar cells which enclose stellate cells. It resembles the dental lamina. The background is composed of embryonic connective tissue containing randomly oriented proliferating fibroblasts. Little collagen is present. Zones of hyalinization, Juxta-epithelial hyalinization, are often found surrounding the epithelial component of the lesion. 18  Odontoma Def.: Odontoma is a hamartomatous lesion commonly found over unerupted teeth, containing enamel, dentin, pulp, and cementum in either recognizable tooth shapes (compound) or (complex), Depending on their resemblance to normal teeth. Because most occur during the period of normal tooth development and often reach a fixed size, they are not considered true neoplasms, but bamartomas. Clinically Age: first and second decades. Site: in the maxilla more than the mandible. Compound odontomas are usually located in the anterior part of the mouth, While complex odontomas are found in the posterior parts of the mandible Radiographically Lesions are usually unilocular, containing multiple radiopaque 19 Compound odontomas may contain as few as 2 to 3 tooth-like structures or as many 20 to 30. While complex odontomas appear as a solid radiopaque mass and are surrounded by a thin radiolucent zone. The lesions are separated from normal bone by a distinct line of cortication. Histopathologically The enamel, dentin, and pulp tissue of the tooth like structures of compound odontoma are arranged as normal pattern. Within the surrounding capsule,. Complex odontoma differs by being composed of a single, disorganized mass of enamel, dentin, and pulp with no recognizable tooth shapes. Islands of spherical calcifications are common in the surrounding connective tissue. Ameloblastic Fibro-Odontoma Def.: Ameloblastic fibro-dontoma , 1- soft tissue components of ameloblastic fibroma and 2- the hard tissue components of complex odontoma. Lesions similar to Ameloblastic fibroma, but also showing inductive changes that lead to the formation of enamel and dentine (Ameloblastic fibro-odontoma). Ameloblastic fibro-odontoma has a potential for growth and local destruction. 20 Clinically Age: It occurs in the first and second decades. Site: posterior areas of the mandible. Pain is rarely associated with this lesion. Radiographically The radiograph exhibits a large, unilocular, well-circumscribed, mixed radiolucent/radiopaque lesion. Most lesions also contain an impacted tooth. Histopathologically The radiolucent areas are composed of soft tissue that resembles ameloblastic fibroma. These areas consist of strands and cords of epithelium that resemble dental lamina against a background of embryonic connective tissue composed of randomly oriented fibroblasts. In adjacent areas, both mature and immature forms of complex odontoma can be found. The lesion is always surrounded by a well- formed capsule. 21