Tumors of Mandible Dr. Ahmed Khan Sangrasi, Assist. Prof, Dept. Of Surgery , LUMHS, Jamshoro

Odontogenic Tumors Ameloblastoma Adenomatoid Odontogenic Tumor: (AOT) Calcifying Epithelial Odontogenic Tumor:  (CEOT) or Pindborg tumor Keratinizing and Calcifying Odontogenic Cyst: (KCOC),  or Gorlin cyst Odontogenic Myxoma Ameloblastic Fibroma Ameloblastic Fibro-Odontoma Complex Odontoma Compound Odontoma Cementoblastoma

1.Ameloblastoma An entirely epithelial tumor arising from the dental lamina, Hertwig sheath, the enamel organ, or the lining of dental follicles/dentigerous cysts Is the most common epithelial odontogenic tumor Usually occur in individuals aged 20-40 years However, the unicystic variant most often occurs in adolescents Lesion occurs in both the maxilla and mandible Posterior mandible is the most common location

Only 20% of lesions are found in the maxilla Distributed equally between males and females Generally is not classified as a malignant lesion (a rare malignant variant exists), it is extremely aggressive and infiltrative Should be considered a low-grade or indolent malignancy, similar to basal cell carcinoma. Generally does not metastasize but is slow growing, persistent, and hard to eradicate

image ; Incisional biopsy revealed the lesion to be an ameloblastoma image ; Incisional biopsy revealed the lesion to be an ameloblastoma. Treatment consisted of segmental resection of the entire mandible from the condyle to the area of the second premolar. The lateral and internal aspects of the resected specimen are depicted.

Symptoms: Noticed as an incidental finding on radiographs taken for other purposes The first symptom is usually painless bony expansion.

Radiographic findings Typically appear as an expansile multilocular radiolucency in the area of the lower third molar, but they may be found anywhere in the jaws Image:  The second radiograph depicts the appearance of the lesion at the second presentation.

Histologic characteristics Does not have a capsule. Neoplastic component is purely epithelial and resembles the cap stage of odontogenesis Lesion may have a reactive connective tissue component that is not neoplastic This is a nonfunctional tumor, ie, it does not induce the surrounding connective tissue, which in turn is unable to induce enamel formation In effect, these tumors represent arrested odontogenesis

Treatment Surgical excision with wide free margins Appropriate reconstruction may be performed at the same time. All patients with ameloblastoma, regardless of surgical treatment method or histologic type, must be monitored radiographically throughout their lifetime If excision is inadequate, recurrence is common. 1-cm clear margins are considered the standard. This may be accomplished with block or segmental resection, depending on the relationship of the lesion to the inferior cortical border. For peripheral ameloblastoma, a more conservative excision with close clinical follow-up is the standard of care.

2. Adenomatoid Odontogenic Tumor: (AOT) Is a fairly uncommon tumor Usually can be easily identified from its clinical and radiographic appearance It often is remembered as the "two-thirds tumor." It most commonly occurs in the second and third decades of life (12-20 y). Two thirds of the cases occur in the anterior maxilla, one third occur in the anterior mandible, and it is never found posterior to the premolars

Two thirds of the cases occur in females, and two thirds of the cases are associated with an impacted tooth (usually the cuspid). This tumor originates from the reduced enamel epithelium of the dental follicle and histologically reproduces the IEE ( inner enamel epithelium) It is generally asymptomatic but may present with mild swelling or in association with a clinically missing tooth.

Radiographic findings Lesion generally appears as a well- demarcated radiolucency In 75% of cases, it is associated with an unerupted tooth, usually the canine May contain radiopaque flecks, which represent calcified material. If associated with a tooth, it generally attaches to the tooth further apical on the root than the typical dentigerous cyst.

Histologic characteristics Technically, this is a hamartoma rather than a true neoplasm because it has a limited growth potential  It has a thick fibrous capsule filled with a proliferation of epithelial elements that form nodules and ductlike structures .  In the absence of connective tissue to induce the formation of enamel, ultimately leave areas of dystrophic calcification and amyloid.

Treatment The recommended treatment of these lesions is simple removal If left alone, these structures probably involute.  However, they can become quite large. Most are removed at biopsy  If it is incompletely removed at biopsy, the literature suggests that the remainder of the lesion degenerates  They are not known to recur.

3. Calcifying Epithelial Odontogenic Tumor: (CEOT) or Pindborg tumor: Is a benign infiltrative odontogenic tumor that is one of the rarest Named after Jens Pindborg, the Danish oral pathologist It is most often found in the mandibular molar/premolar region, but 33% of cases are found in the maxilla  It is associated with an unerupted or impacted tooth in 50% of cases CEOT is an infiltrative neoplasm and causes destruction with local expansion It is derived from the stratum intermedium and has a lower growth potential than ameloblastoma. Not surprisingly, it is less aggressive than ameloblastoma.

Radiographic findings These lesions can be radiolucent, but they more characteristically are mixed lucent and opaque masses, exhibiting a snow-driven appearance. Histologic characteristics : Histologic view of this lesion is worrisome because it appears as invasive infiltrative islands in bone These islands look like pure squamous cells with a high degree of nuclear pleomorphism However lack of mitotic figures help to distinguish this lesion from squamous cell carcinoma

Treatment: The treatment of this lesion is complete surgical excision The recurrence rate for CEOT is 4% The lesion is slow growing and requires long- term follow-up monitoring for recurrence (at least 5-10 y). No cases of malignant transformation are reported.

4. Keratinizing and Calcifying Odontogenic Cyst: (KCOC),  or Gorlin cyst: Is not actually a cyst but rather a neoplasm with cystic tendencies Some KCOC lesions are actually solid This is a very rare lesion with no age, sex, or location predilections. May be found anywhere in the jaws, and one fourth of lesions are found in peripheral soft tissue (eg, gingiva).  If KCOC is not discovered as an incidental finding on radiographic examination, the earliest clinical presentation usually is a localized swelling. These lesions arise from a more mature enamel epithelium than ameloblastoma, and, accordingly, they have less growth potential.

Radiographic findings: These are nondescript radiolucencies that may contain flecks of opacity They may become quite large if not discovered serendipitously.

Histologic characteristics Lesions are lined by an epithelium that is similar in appearance to ameloblastoma Appears somewhat similar to the unicystic ameloblastoma, with masses of keratinized squamous epithelial cells within the SR(stellate reticulum) However, these cells have no nuclei and are called ghost cells. Simply, this lesion represents enamel epithelium that has a tendency to mature but is unable to form enamel Treatment: These lesions are surgically removed and rarely recur after excision.

5. Odontogenic Myxoma: This is a benign infiltrative lesion that is clinically indistinguishable from ameloblastoma It is found in tooth-bearing areas, and a slight predilection for the mandible exists  It generally appears in the early third to fourth decades of life as a slow-growing expansile lesion If odontogenic myxoma is left untreated, it is invasive and destructive It is derived from dental mesenchyme (papilla) or follicle.

Radiographic findings : The radiographic appearance of this lesion is not distinctive.  It appears quite similar to ameloblastoma (eg, multilocular radiolucency), though some authors believe that the individual loculations are somewhat smaller in odontogenic myxoma (myxofibroma).

Histologic characteristics: A few stellate fibroblasts with copious amounts of hyaluronic acid, scant collagen fibrils, and no capsule describe the histologic appearance of this lesion. The hyaluronic acid component stains with Alcian blue, reminding one of the appearance of Wharton jelly. This lesion looks like developing pulp and may be confused with a developing third molar.

Treatment: As with ameloblastoma, this lesion is treated with block excision Recurrences occur although with somewhat less frequency than with ameloblastoma

6. Ameloblastic Fibroma Is a true mixed tumor arising from a combination of 2 embryonic tissues The epithelial component is able to induce mesenchyme but not to the extent of developing dental hard tissues It is a relatively uncommon tumor of young people (aged 5-20 y); 75% of ameloblastic fibromas are found in the posterior mandible in the area of a developing tooth. It is benign and expansile, growing as a pushing front rather than invading surrounding tissues.

Radiographic findings: This lesion appears as a uniocular or bilocular radiolucency, most often in the posterior mandible. Appearance is identical to that of unicystic ameloblastoma, and both lesions should be differential diagnoses because they affect similar age groups and have similar clinical and radiographic appearances Histologic examination differentiates the two.

Histologic characteristics The epithelial component of this lesion is almost identical to that of ameloblastoma; However, the connective tissue component looks like dental pulp. It is a young, cellular, homogenous connective tissue without much dense collagen The epithelial and connective tissue components grow together inside a capsule.

Treatment The treatment of this lesion is block excision with a border of normal bone With simple enucleation, recurrence rates of 20-40% have been reported. Sarcomatous change (ameloblastic fibrosarcoma) has also been reported with recurrence or inadequate excision.

7.Ameloblastic Fibro-Odontoma: Is an extremely rare odontogenic lesion that develops dental hard tissues (eg, dentin, enamel, cementum) It appears most often before age 20 years and has a slight predilection for the premolar area in either jaw Although these lesions can become quite large, they generally do not have much growth potential.

Radiographic findings Appears as a well-demarcated radiolucency with a large central opacity Lesions almost always are found in association with a tooth. Some similarity exists in radiographic appearance to that of the Pindborg tumor and Gorlin cyst because this is a mixed radiolucent/radiopaque lesion

Histologic characteristics This lesion has the histologic characteristics of ameloblastic fibroma However, epithelial induction of connective tissue occurs to the point of histodifferentiation, leading to presence of dentin, enamel, and/or cementum in the microscopic presentation.

Treatment Surgical excision of ameloblastic fibro- odontoma is the usual proposed treatment These lesions do not often recur. The literature contains some support for sarcomatous change with recurrence.

8.Complex Odontoma; Represent further histologic differentiation of the odontogenic pluripotential epithelium Findings from this lesion resemble those of ameloblastic fibro-odontoma but extended one step further The epithelium in this lesion has involuted, leaving disorganized dental hard tissues in place These are common lesions, and they persist throughout life They are usually detected in adolescence and have a predilection for the mandibular molar regions; however, they can be found in other areas of the jaws.

Radiographic findings Lesions are generally described as sunburst radiopacities surrounded by a thin, uniform, radiolucent rim.  Have some superficial resemblance to the radiographic description of osteosarcoma,  The association with a tooth, the clear demarcation of the lesions' borders, and the lack of pain and/or swelling serve to delineate this very benign lesion from osteosarcoma.

Histologic characteristics Physiologic reduction of the ameloblastic epithelium is found. A mixed honeycomb presentation of enamel, cementum, dentin, and pulpal tissue is present Treatment Simple removal or radiographic observation is the method of treatment These lesions do not recur.

9.Compound Odontoma: This is the most common odontogenic tumor.  It is most commonly found in the maxillary anterior alveolar bone But may be located anywhere within the tooth-bearing segments of the jaws. It is often responsible for preventing normal tooth eruption, thus it is usually discovered during adolescence. Radiographic findings Multiple tiny toothlike structures are contained within a fine radiolucent rim.

Histologic characteristics Histology of compound odontomas approaches normal tooth structure Gross clinical examination is usually sufficient for diagnosis. Treatment Simple removal is the method of treatment These lesions do not recur.

10.Cementoblastoma: Cementoblastoma, as distinguished from cementoma, is a true neoplasm of cementum This benign neoplasm is rare and is usually observed in patients younger than 25 years It is most often found in association with the apex of the mandibular first molars (50% of lesions), and it is never found in association with the anterior dentition. The lesion is usually asymptomatic, although occasionally the associated tooth may be slightly sensitive to percussion.

Radiographic findings A round opaque sunburst mass attached to the apex of a tooth that is well-demarcated and surrounded by a thin radiolucent rim is observed The lesion obscures the lamina dura Sometimes confused with condensing osteitis, a common lesion resulting from low- grade periapical irritation that stimulates bone growth

Histologic characteristics Plump cementoblasts separated by cemental partitions form the histology of this encapsulated lesion. Treatment Removal of attached tooth and tumor is the method of treatment. No recurrences are reported.