------------------------------------------------------------------------------ TITLE: ODONTOGENIC TUMORS AND CYSTS SOURCE: Dept. of Otolaryngology, UTMB, Grand Rounds DATE: December 2, 1992 RESIDENT PHYSICIAN: Denise Guendert, M.D. FACULTY: John Kinsella, M.D. DATABASE ADMINISTRATOR: Melinda McCracken, M.S. ------------------------------------------------------------------------------- "This material was prepared by resident physicians in partial fulfillment of educational requirements established for the Postgraduate Training Program of the UTMB Department of Otolaryngology/Head and Neck Surgery and was not intended for clinical use in its present form. It was prepared for the purpose of stimulating group discussion in a conference setting. No warranties, either express or implied, are made with respect to its accuracy, completeness, or timeliness. The material does not necessarily reflect the current or past opinions of members of the UTMB faculty and should not be used for purposes of diagnosis or treatment without consulting appropriate literature sources and informed professional opinion." I. TOOTH DEVELOPMENT A. Odontogenesis -Four stages of tooth development: 1. dental lamina stage 2. bud stage 3. cap stage 4. bell stage -In 1 and 2, a band of epithelium forms along future alveolus. Epithelial downgrowth forms invaginations into underlying ectomesenchyme. -In 3, cells of epithelium differentiate histologically forming inner and outer enamel epithelium. Changes also occur in the underlying ectomesenchyme forming the dental papilla and dental sac. -In 4, the inner enamel epithelium differentiates into tall columnar cells which become ameloblasts and are eventually responsible for amelogenesis or enamel formation. The underlying dental papilla cells differentiate into odontoblasts which are responsible for dentin production. Lingual to primary tooth, dental lamina gives rise to the enamel organ of the permanent tooth. -Dentin formation begins at incisal region of tooth and progresses towards root. Amelogenesis begins adjacent to forming dentin and proceeds to incisal edge. -Normal amelogenesis relies on normal dentinogenesis. -As dentin grows into root the surrounding dental sac forms a calcified layer called cementum. It also forms the periodontal ligament. B. Derivation of Odontogenic Cysts and Tumors 1. Enamel epithelium of tooth crown 2. Epithelial rests of Malassez - remnants of root sheath which is the epithelial network that guides root formation. 3. Epithelial rests of Serres - remnants of primary tooth dental lamina after formation of permanent tooth lingually. 4. Tooth germ itself. 5. Ectomesenchymal cells. II. ODONTOGENIC CYSTS A. Inflammatory Cysts -Thought to arise from proliferation of normally quiescent epithelium such as the rests of Malassez upon activation by inflammation resulting from pulpitis and subsequent granuloma formation followed by cyst formation. 1. Periapical (Radicular Cyst) -Most common odontogenic cyst reported at 50-75%. -Majority of these are asymptomatic though association with nonvital or decayed tooth may lead to c/o pain. Rarely associated with fistula to skin or oral mucosa. -Most common at 20 to 50 years with peak in 20s. -Slightly higher incidence in men ~60%. -Highest incidence in anterior maxilla followed by posterior mandible. Maxillary central incisors most common. -Xray: Solitary radiolucent area attached to root apex of diseased tooth surrounded by sclerotic bone. May have concurrent cysts on root apices of multirooted molar. -Histology: Lining is nonkeratinizing stratified squamous epithelium. See chronic inflammatory cells in connective tissue. May see mucous cells, cholesterol and lipid-laden macrophages. -Rx: Root canal or tooth extraction to treat infection, lesion should then resolve, if not, enucleate. 2. Lateral Inflammatory Periodontal Cyst -Not to be confused with developmental lateral periodontal cyst. -Same as apical except for formation in this case is along lateral aspect of tooth. B. Developmental Odontogenic Cysts -These comprise 10%-18% of all jaw cysts. 1. Gingival Cysts of Infants (Dental lamina cysts, Epstein's Pearls) -Small, often multiple, keratin-filled cysts found on palate and alveolar ridges of young infants. -Those on palate thought to arise from epithelial islands entrapped during fusion of palatal folds and nasal processes. Those of alveolar ridge represent keratinized remnants of dental lamina. -Median palatal raphe is most common site followed by maxilla. -Clinical: Multiple raised white or pink nodules 1-5 mm in diameter. Rarely occur in children >3 months. -Incidence reported at 68-85%. -Histology: Lined by thin keratinizing squamous epithelium that lacks corrugated appearance and columnar basal layer of keratocyst. -Behavior: Majority discharge keratin shortly after birth and require no treatment. After keratin discharged, cyst wall fuses with oral mucosa. 2. Gingival Cyst of Adults -Epithelium-lined cyst that occurs in the gingival soft tissue and may cause bony erosion but does not arise within bone. -Thought to result from cystic degeneration of remnants of the dental lamina. -Incidence .15-.3% -More common in mandible (77%) in premolar region on buccal surface. -Majority occur 40-59 years of age. -Male-60% -Clinical: Painless, circumscribed swelling on gingiva either white, red, or blue-gray, usually less than 1 cm. and soft. -Xray: Pressure resorption of underlying bone- saucer shaped. -Histology: Similar to that of infant. -Rx.: Simple excision. -Behavior: Grow slowly and tend not to recur. 3. Eruption Cyst -Result of degenerative cystic changes in the reduced enamel epithelium after completion of amelogenesis. -Bluish, translucent, dome shaped lesion of the alveolar ridge overlying an erupting tooth. -Occur in 11% of infants during eruption of deciduous incisors and 30% of infants during eruption of deciduous canines and molars. -Histology: Lined by nonkeratinizing stratified squamous epithelium. Hemorrhage often occurs into cyst. -Rx: Unroofing of cyst if delay in eruption of tooth or superimposed infection. 4. Lateral Developmental Periodontal Cyst -Cyst located lateral to the root of a vital tooth (not of inflammatory origin) -Thought to arise from dental lamina rests. -Incidence of 1.5-2.8%. -Occurs twice as often in males. -Most commonly occurs in mandible (74%) in incisor-cuspid- premolar area. -Clinical: Asymptomatic usually noted on routine xrays. -Xray: Characteristic appearance of a round or ovoid radiolucency, with sharply defined margins, < 1 cm, and lateral to root of vital tooth. May have displacement of adjacent teeth. -Histology: Lined by nonkeratinizing squamous epithelium, glycogen rich clear cells may be present. Usually no inflammatory cells present. -Rx: Enucleation with preservation of adjacent tooth. -Behavior: No tendency to recur. 5. Follicular or Dentigerous Cyst -Most common developmental cyst. -Encircles crown of unerupted permanent tooth. -Thought to originate from accumulation of fluid between reduced enamel epithelium and completed tooth crown. -Usually found in mandible in third molar region. Canine is most common site in maxilla. -Most common in second, third and fourth decades. -~60% occur in men. -Clinical: unerupted tooth most common finding. Asymptomatic though may develop pain, facial swelling/asymmetry secondary to bony expansion and displacement of teeth when large. -Xray: Unilocular radiolucency with well defined sclerotic margin encircling crown of unerupted tooth. May see expansion of cortex, displacement of surrounding teeth if large. -Hist.: Cyst composed of thin connective tissue wall lined by stratified non-keratinizing squamous epithelium that is continuous with the reduced enamel epithelium covering the tooth crown. May see inflammatory cells in surrounding tissue and occasional foreign body giant cells. -Rx: enucleation or decompression followed by enucleation if large. -Prognosis: Recur with incomplete removal. Potential to form ameloblastoma. Also potential for transformation into central epidermoid carcinoma of the jaw (75% associated with dentigerous cyst) and central mucoepidermoid carcinoma of the jaw (18% association with dentigerous cyst). 6. Odontogenic Keratocyst -Frequency range reported at 3-22% with mean of 9.2%. -Microscopically distinct form of odontogenic cyst that may assume character of any of the odontogenic cysts. It may be associated with the crown of a tooth and therefore appear as dentigerous cyst or it may be associated with root like a lateral periodontal cyst. -Felt to arise from the rests of seres, or basal cell hamartia of the overlying oral mucosa. -Age range 7 to 78 with peak in second and third decades. -Sex distribution- 60% male -Most common site is mandibular third molar followed by maxillary third molar. 75% in mandible. -Multiple cysts occur in 7%. One third of these patients have nevoid basal cell carcinoma syndrome. Multiple cysts also reported in Marfan's syndrome and Noonan's syndrome. -Clinical: Approximately 50% are symptomatic with pain, swelling, trismus, drainage, parasthesias. -Xray: ~60% have unilocular radiolucency others are multilocular. Well defined sclerotic border. Surrounding teeth may be displaced and adjacent cortex may be expanded or perforated. The latter is more common than with other cysts. -Hist.: Thin keratinizing stratified squamous epithelium. Parakeratotic surface in 80-97% of cases. Well defined basal- cell layer of palisaded columnar cells. May have budding of the basal layer. Fibrous wall is thin and occasionally with presence of cholesterol, hyalin bodies and inflammation. May have satellite cysts in wall. Lumen contains desquamated keratin. -Rx.: For small cysts, enucleation and curettage adequate. For For larger cysts many recommend marsupialization or decompression with polyethylene drainage tube followed at a later date by enucleation and curettage. Recurrent keratocysts may require marginal or segmental mandibular resection. -Prognosis: Recurrence rate ranges from 5%-62%. Must therefore follow radiographically for at least 5 years. Recurrences have been reported as late as 37 years after excision. Keratocysts of patients with NBCCS have higher recurrence rate. a. Nevoid Basal Cell Carcinoma Syndrome -Autosomal dominant gene with variable but high penetrance. No sex or racial predilection. -Principle characteristics are multiple odontogenic keratocysts (in 65-77% of patients), multiple basal cell carcinomas at an early age (usually onset at 7-14 years), dyskeratotic pitting of hands and feet, ectopic soft tissue calcification, frontal and parietal bossing, bifid ribs, calcification of the falx cerebri, and vertebral anomalies such as spina bifida, fusion. -A typical patient will have thousands of basal cell carcinomas and it is not practical to remove all. Although Basal cell carcinomas generally act benign, some may become highly destructive. Those that demonstrate increased growth, ulceration or bleeding should be excised -These patients should have keratocysts managed as above and should be advised of high rate of recurrence and new cyst formation. Periodic radiographic follow up required. 7. Primordial Cyst -Arise from a developing tooth that fails to differentiate. The odontogenic epithelium becomes cystic prior to the formation of dental hard tissues. -Controversy regarding terms primordial cyst verses odontogenic keratocyst. Most agree that keratocyst designates characteristic histologic appearance and behavior and primordial refers to association with absent tooth. -Seen in children and young adults. -No sex predilection. -Most common locations are third molar region of mandible. -Clinical: Asymptomatic unless secondarily infected. -Hist: That of Keratocyst in 44% otherwise have non- keratinizing squamous epithelium. -Xray: Well demarcated unilocular radiolucency in place where tooth would normally develop. -Rx: Same as keratocyst 8. Calcifying Odontogenic Cysts (Gorlin cysts) -Cyst associated with unerupted teeth or complex odontomas. -Most occur in intraosseous location but some are extraosseous. -Incidence <2%. -Age range 7-82 years with peak in second decade. -No sex predilection. -Nearly equal distribution between maxilla and mandible with a site anterior to the first molar most common. -Clinical: 50% complain of swelling and pain in less than 20%. -Xray: Intraosseous lesions usually appear as unilocular radiolucencies with well defined borders. Some may be multilocular or have irregular radiopacities. Extraosseous lesions may cause saucerization of underlying bone. -Histology: Squamous epithelium with prominent columnar basal layer and loose appearing middle layer. Cells toward lumen exhibit keratolysis (ghost cell) and some may have dystrophic mineralization. Dysplastic dentin, multinucleated giant cells and melanin may be present. -Rx: Enucleation with careful sampling of specimen because of association with more aggressive lesions. -Behavior: Rare recurrences, but are associated with ameloblastoma, ameloblastic odontoma, and complex odontoma. C. Lesions in Differential for Odontogenic Cysts 1. Aneurysmal Bone Cyst -Not true cyst -Predilection for females. -mandible most common site in craniofacial skeleton. -Thought to arise from giant cell granuloma. -Clinical: selling and pain common features. -Xray: Radiolucency with multilocular appearance. Tends to have sclerotic bone margins. -Rx: Enucleation. Common to have significant bleeding during removal which is controlled with rapid and complete removal. -Behavior: Do not recur. 2. Idiopathic Bone Cavity -Initiated by trauma and subsequent intramedullary hemorrhage. -Usually occurs in second decade. -Asymptomatic -Xray: Unilocular radiolucency that surrounds teeth and does not distort or displace them. -Rx: Biopsy to R/O other lesions. III. Odontogenic Tumors A. Epithelial Odontogenic Tumors 1. With Minimal Inductive Change in Connective Tissue a. Ameloblastoma -Thought to arise from rests of Serres or Malessez, epithelial lining of dentigerous cyst, or basal cells of oral epithelium. -Compose 11% of odontogenic tumors. -Usually diagnosed in third through fifth decade. -Nearly equal distribution between sexes. -Occur four times as often in mandible than maxilla. Usually in molar region. When in maxilla may extend to maxillary sinus even orbit. -Clinical: Early symptoms are absent. Later, patients may complain of slow growing, painless swelling. 75% will c/o swelling only 33% c/o pain. May also have loose teeth, ill-fitting dentures, malocclusion, purulent nasal drainage, nasal obstruction. -Xray: Radiolucent without calcification. May appear unilocular, with or without association with tooth and be indistinguishable from dentigerous cyst (~20%), or may be multilocular. -Histology: Two predominant patterns i. Follicular- Epithelial islands within fibrous stroma central areas of loose stellate reticulum. ii.Plexiform- Islands of mature fibrous stroma are intermingled with strands of epithelium. May have both patterns but one predominates. Both have characteristic cells at periphery of epithelial islands, these cells are columnar with nuclei polarized away from basal membrane (mimics inner enamel epithelium). May have mucin producing cells, numerous blood vessels in stroma, neuromatous elements. -Rx: excision with 1-2 cm margins yields lowest recurrence rate (4-5%). Higher recurrence rates with enucleation and curettage (55-90%). Marginal mandibular resection may be necessary. Less likely to require segmental resection. Immediate reconstruction is legitimate undertaking. XRT recommended in disseminated disease or tumors beyond surgical reach. Neck dissection only in patients with obvious cervical adenopathy. -Behavior: Usually intermittent rapid growth. High recurrence rates as noted above. Lower recurrence rates with unilocular lesions. Those less than 20 at time of excision have better prognosis. Tumor usually contained by periosteum, but may perforate through and invade surrounding tissues. 20 cases of malignant ameloblastoma reported with spread to lungs, nodes, spleen, liver. -Variant is the peripheral ameloblastoma that has microscopic features of ameloblastoma, but arises in the soft tissue overlying the tooth bearing region. Appear as painless, sessile, firm, sometimes exophytic lesion usually on lingual gingiva of the mandible. Recurrences are uncommon after excision (<20%). b. Adenomatoid Odontogenic Tumor -Some consider this a hamartomatous lesion. -Origin remains unknown. Possibly outer or inner enamel epithelium. -Incidence 3% of odontogenic tumors. -70-80% occur between 10 and 20 years. -Twice as common in females. -More common in the maxilla(66%), and usually involve anterior region(76%). 74% associated with impacted permanent teeth (Giansanti). -Clinical: Most commonly painless swelling usually intraorally (60%) verses extraorally (20%). Less common complaints of pain, loose teeth. -Xray: Unilocular radiolucency around crown of impacted tooth, resembling dentigerous cyst. May see calcifications. Margins are usually well-defined and sclerotic. -Histology: Thick-walled cystic structure with prominent intraluminal ductlike proliferation of odontogenic epithelium. Eosinophilic amorphous material (enamel matrix) between epithelial ducts. Calcifications present either as rings or dystrophic bodies. -Rx: Enucleation -Behavior: Very rare recurrence. c. Calcifying Epithelial Odontogenic Tumor (Pindborg Tumor) -Thought to arise from either reduced enamel or inner enamel epithelium. -Incidence is 1-1.8% of odontogenic tumors. -Usually in 30-40 year age group. -No sex predilection. -Two-thirds occur in mandible, usually molar region. 50% associated with unerupted or impacted tooth. -Clinical: Usually complain of painless, slow-growing mass. May have nasal congestion, epistaxis, pain. -Xray: Variable. May be radiopaque, lucent, or have calcifications. Most commonly have unilocular radiolucency. -Histology: Characteristic with sheets of polyhedral epithelial cells with prominent borders, intercellular bridges, and ring-like calcifications. Eosinophilic substance in fibrous stroma and cytoplasm of tumor cells that stains positive with amyloid stains. -Rx: Most recommend resection with 1-2 cm margins as this tumor locally invasive like ameloblastoma, though recurrence rate is less than ameloblastoma (14%). d. Squamous Odontogenic Tumor -Very uncommon. -Thought to arise from rests of Malassez. -Age range of 11 to 67 years with 66% occurring in patients less than 32 years. -Slight female predilection (57%). -Equal distribution between maxilla and mandible. Incisor- canine region of maxilla and premolar region of mandible are most common sites. -Clinical: Most common symptom is tooth mobility,~50%. -Xray: Well defined semicircular radiolucency that involves the alveolus and surrounds the tooth roots. More likely to perforate the cortex of maxilla and spread into surrounding tissues than in mandible. -Histology: Multiple, irregularly shaped islands of squamous epithelium in a mature fibrous stroma. Peripheral epithelial cells are flattened and do not resemble those of the ameloblastoma. Rare keratinization and calcification. -Rx: Extraction of adjacent tooth with excision and curettage of lesion. -Behavior: Rare recurrence. 2. With Marked Inductive Change in Connective Tissue. a. Ameloblastic Fibroma -Histologically resembles ameloblastoma but occurs at a younger age and behaves less aggressively. -Thought to result from proliferation of ameloblasts that subsequently induce the formation of ectomesenchyme. -Accounts for ~2% of odontogenic tumors. -Age range 6 months to 42 years with the average age 14.6. 40% occur before 10 years. -Equal sex distribution. -Marked tendency to affect mandible (83%). Usually in molar region. -Clinical: Painless swelling (60%). Common to complain of disturbance of tooth eruption. -Xray: Sharply defined radiolucency with sclerotic border. Usually multilocular. Expansion of cortex common but perforation rare. 3 of 4 tumors associated with unerupted tooth. -Histology: Scattered strands, rosettes or islands of odontogenic epithelial cells (cuboidal or columnar), in an immature stroma that resembles dental papilla. Stroma more primitive than that in ameloblastoma. Tumor well-encapsulated. -Rx: Enucleation with curettage. -Behavior: Recurrence ~18%. Malignant counterpart is the ameloblastic fibrosarcoma and should follow radiographically on annual basis as malignant tumors have originated from recurrences. b. Ameloblastic Fibrosarcoma -Malignant counterpart of the ameloblastic fibroma. -Age range 13 to 78 years with average of 31 years. -Equal sex distribution. -More common in mandible, usually in molar region. -Clinical: Most common complaints are pain and swelling. May also have ulceration, paresthesias of lower lip. -Xray: Poorly defined multilocular radiolucency, with gross expansion and thinning of cortices and root resorption. -Histology: Differs from fibroma by exhibiting sarcomatous stroma. Stroma appears as interlacing pattern of spindle cells with numerous mitosis. Odontogenic epithelium is benign appearing. -Rx: Wide surgical excision. XRT not proven to be effective. -Behavior: Very high recurrence rate, with majority of cases characterized by multiple recurrences. Few reports of metastases. c. Odontoma -Classified as tumor, but may be better defined as a hamartoma. -Derived from functional ameloblasts and odontoblasts and formation of enamel and dentin in abnormal pattern. -Two major subcategories are the complex odontoma and the compound odontoma. i. Complex Odontoma -Malformation in which all dental tissues are represented, with all individual tissues being well-formed but occurring in disorderly pattern. -Regezi reported incidence of 30% of all odontogenic tumors. 51% of odontomas are complex. -Average age of detection 14.8 years. -Equal sex distribution. -More common in mandible (56%), usually in posterior region. -Clinical: Swelling if buccal plate is most common first sign. Pain occurs in ~50% and absence of tooth in 75%. -Xray: Single irregular radiopaque mass surrounded by narrow radiolucent band. -Histology: Mixture of enamel, dentin, pulp tissue, and cementum arranged in disorderly fashion. -Rx: enucleation -Behavior: Do not recur. May cause displacement or resorption of surrounding teeth. ii. Compound Odontoma -Malformation in which all the dental tissues are represented in more orderly pattern than complex variety. -49% of odontomas are compound. -Average age at detection is 20.3 years. -Equal sex distribution. -78% occur in the maxilla, usually in anterior region. -Clinical: Same as complex odontoma. -Xray: Multiple tooth-like radiopacities with surrounding narrow radiolucent band. -Histology: Mixture of enamel, dentin, pulp tissue and cementum arranged in orderly fashion. -Rx: Enucleation. -Behavior: Same as complex. B. Mesodermal Tumors 1. Odontogenic Fibroma -Uncommon tumor thought to arise from periodontal ligament -Mean age at diagnosis is 34 years. -Equal sex distribution. -80% located in mandible. Peripheral odontogenic fibroma of involving gingiva in solitary or diffuse pattern has been reported. -Clinical: Slow persistent growth that results in asymptomatic cortical expansion. -Xray: Multiloculated radiolucency associated with unerupted or displaced tooth. Smooth borders. -Histology: Cellular fibrous connective tissue stroma with variable strands or nests of inactive odontogenic epithelium. -Rx: Enucleation -Behavior: Only one recurrence reported in literature. 2. Myxoma -Arises from primitive mesenchyme, perhaps the periodontal ligament. -Relatively uncommon, ~3% of odontogenic tumors. -60% occur within the second or third decade. -Equal sex distribution. -Slightly more common in the mandible. Occurs in posterior region. -Clinical: Slow progressive swelling and bony expansion. Mobile teeth, malposed teeth, and unerupted teeth are often present. Facial asymmetry may be prominent. Rarely associated with pain. -Xray: Unilocular or multilocular radiolucency with indistinct borders. Septa may create honeycomb appearance. Bony cortex may be thinned or perforated. In maxilla, tumor may extend to involve sinus. Unerupted or missing tooth may be seen. -Histology: Stroma composed of homogeneous ground substance that is slightly basophilic and rich in hyaluronic acid. Scattered throughout this substance are stellate cells with branching cytoplasmic processes. -Rx: Grossly gelatinous or mucoid and curettage is therefore not recommended for likelihood of leaving cells behind. Wide excision indicated with 1 cm. margins. -Behavior: recurrence reported at up to 33%. No metastatic potential, but locally aggressive. 3. Cementoma -This term encompasses several lesions all derived from the periodontal membrane which possesses the ability to produce cementum, alveolar bone, and fibrous tissue. Under pathological conditions, blastic cells from this membrane can produce tumors composed of any of the above tissues alone or in combination. a. Periapical Cemental Dysplasia. -The most common lesion of the cementoma category, accounts for 8% of odontogenic tumors. -Develops at the root apex of a vital tooth. -14 to 1 female to male ratio. 70% in Afro-americans. -Usually occurs between 25 and 45 years. -More than 90% are in the mandible, usually involving and incisor or canine tooth. -Most are less than 1 cm. and 70% of patients will have multiple lesions. -Clinical: Asymptomatic, usually discovered on routine radiographs. -Xray: Initial osteolytic stage with resultant periapical radiolucency, followed by calcifying or cementoblastic stage and resultant mixed radiolucent-radiopaque appearance. Final stage is the mature stage associated with finding of radiopaque lesion with thin radiolucent border. -Histology: Early stage appears as a cellular fibrous stroma without mineralization. Next stage contains various amounts of cementoid matter. The last stage reveals coalescence of mineralized matter into mass of cementum. -Rx: Self-limiting lesion that does not require treatment. Tendency for this lesion to burn itself out.Does require periodic radiographs to assure diagnosis. If lesion continues to grow or cause expansion, biopsy is indicated. b.Benign Cementoblastoma -Comprises less than 1% of odontogenic tumors. -50% of tumors detected between 10 and 20 years. -55.6% occur in males. -75% occur in the mandible, usually the first molar. All lesions in the mandible have been associated with single tooth, while those of maxilla may be associated with multiple teeth. -Clinical: Most common findings are expansion of jaws, facial asymmetry, swelling. 50% complain of pain. -Xray: well-circumscribed, round, radiopaque mass with a radiolucent border that is fused to single or multiple teeth. Roots may be partially resorbed. -Histology: Central mass of cementum which is fused to the tooth root. At the periphery is a cellular fibrous stroma and cemental trabeculae bordered by numerous, large, hyperchromatic cementoblasts. -Rx: The tooth/teeth and accompanying fused mass should be excised together (enucleation). -Behavior: No tendency to recur but unlimited growth potential if left untreated. c. Cementifying Fibroma -~2% of odontogenic tumors. -More than 50% occur between 20 and 40 years. -84% in females. -86% occur in the mandible. Usually in premolar-molar region. -Clinical: Painless slowly progressive swelling. May cause displacement of teeth. -Xray: Solitary, well-circumscribed, radiolucent or radiopaque lesion. -Histology: Immature cellular fibrous stroma containing scattered droplets of acellular cementum. -Rx: Enucleation. -Behavior: Rare recurrence after enucleation. d. Gigantiform Cementoma -Thought to be inherited as a autosomal dominant disorder. -Rare growth seen most often in middle aged Afro-american women. -Characterized by progressive expansile growth in several regions of the jaw resulting in marked facial deformity. -Xray: ill-defined radiolucent to radiopaque lesions. -Histology: Dense fibrous connective tissue with cementum and lamellar bone in various configurations adjacent to active bone resorption. -Rx: May require aggressive excision if symptomatic or complicated by osteomyelitis. IV. Diagnosis of Odontogenic Cysts and Tumors A. History and Physical -Question about pain, swelling, tooth mobility, unerupted teeth, h/o tooth extraction, nasal drainage, headaches, change in vision, oral lesions, paresthesias, fevers, malocclusion, change in fit of dentures. -Examine for facial asymmetry, tenderness, malocclusion, decreased sensation in V3, widening of alveolar ridge, skin lesions, etc... B. Radiographs 1. Routine Dental Films -Often discovered on routine films. -Good for examining individual teeth for decay. 2. Panorex -Better than routine dental films for defining extent of larger tumors and cysts. 3. CT Scan -Not cost effective for evaluating most cysts or tumors. -Is indicated for defining extent of very large lesions and for assessing extension outside of cortex into surrounding tissues. 4. Key Radiographic findings -Benign lesions tend to displace vital structures and cause bony expansion, leaving cortical bone intact. -Benign lesions usually have well-defined border. -Aggressive lesions tend to resorb tooth roots, grow fast, erode cortical bone, and spread into surrounding tissues. -Aggressive lesions are also poorly delineated. C. Biopsy -Fine needle aspiration excellent for ruling out vascular lesion. If white keratin debris obtained lesion very likely is keratocyst. Will be helpful to diagnose inflammatory lesions or lesions with secondary infection. -Many feel incisional biopsy indicated, especially in lesions that appear more aggressive to obtain diagnosis prior to definitive surgical approach excision. -Excisional biopsy indicated for small radiographically benign lesions that are readily accessible or when access is more invasive than removal (lesions of condyle or lesions in children when general anesthesia required for biopsy) V. Surgical Therapy A. Goals 1. Obtain definitive diagnosis 2. Ensure complete removal -prevent recurrence -remove all potential neoplastic foci and assure no malignant foci 3. Preserve or restore function -develop reconstructive ideas prior to surgery in case they are needed -Maintain vital teeth 4. Minimize cosmetic defect B. Methods 1. Marsupialization -Creation of communication between epithelium of cyst and oral cavity. Antrocystectomy is form in which cyst drained into maxillary sinus. -Allows decompression and resolution of cavity. -Communication may be maintained by placement of drain or packing opening. -Indications: a.Very large cysts with bony expansion. b.Cysts impinging on orbit, pterygoid region, nasal cavity. c.Patients with medical problems which contraindicate major surgery. d.In combination with enucleation. -Disadvantages include requirement for daily irrigations and this method does not allow histopathologic investigation of entire lesion. 2. Enucleation -Lesion is shelled out of bony confines. -Primary closure with suture line over sound bone adequate for smaller lesions. Larger lesions more commonly packed open with antibiotic gauze with daily dressing changes required. -Bone grafting of cystic cavities is performed by some to shorten time required for bone to fill in. This is not necessary if bone has adequate functional strength after removal of lesion. -Indicated when any suspicion of neoplasm exists. -More successful reduction in recurrence if combined with curettage either with large bone burr or bone curette. 3. Decompression Followed by Enucleation -Decompression performed first to shrink cyst followed several weeks later by enucleation. -Several advantages: a. Lessens amount of bone removed. b. Decreases risk of perioperative fractures. c. Decreases risk to adjacent structures (teeth, nerves etc...) 4. Marginal Mandibular Resection -Superior (alveolar) marginal resection leaves inferior border of mandible intact. -Allows better postoperative function than segmental resections. -Allows better stabilization of grafts. 5. Segmental Partial Mandibulectomy -Resection of primary lesion in continuity with complete segment of surrounding mandible. -Leaves discontinuity between two remaining segments. 6. Hemimandibulectomy -Resection of 1/2 the mandible to the condyle. Sometimes refers to resection extending from midline to angle. 7. Total Mandibulectomy -Refers to removal of segment from angle to angle or any resection more extensive. C. Reconstruction and Stabilization -Arch bars and external fixators are useful adjuncts to mandible surgery especially if there is a risk of fracture either secondary to lesion itself or resection of lesion. -Some place patients in arch bars routinely during convalescence to minimize chance of fracture. -Plates may be used either to support graft, maintain fragment position, or bridge defect. -Particulate autogenous marrow is graft material of choice in restoring defects at time of surgery if rapid osteogenesis is the aim. -If lesion is benign, resection is not extensive, XRT not planned and layered oral closure is permitted, immediate reconstruction using titanium mesh tray packed with autogenous marrow or reconstruction plate with or without cancellous or corticocancellous bone graft may be performed. ----------------------------------------------------------------------------- BIBLIOGRAPHY 1. Assael, L.: Benign Lesions of the Jaw, Oral and Maxillofacial Surgery Clinics of North America, Volume 3 no. 1,Feb. 1991, W.B. Saunders Co., pages 1-109 and 127-165 2. Bailey, B. and Holt, R: Surgery of the Mandible, 1987, Thieme Medical Publishers Inc., New York, Chapters 5 and 6 3. Batsakis, J.: Tumors of the Head and Neck, Clinical and Pathological Considerations, Second edition,1979, Williams and Wilkins, Baltimore, Chapter 27 4. Brondum, N. and Jensen, V: Recurrence of Keratocysts and Decompression Treatment, Oral Surgery, Oral Medicine, Oral Pathology, September 1991, pages 265-269 5. Cummings, C., etal: Otolaryngology-Head and Neck Surgery, Second Edition, Volume 2, Mosby Year Book, Pages1415-1450 6. Eversole, L.: Clinical Outline of Oral Pathology, Diagnosis and Treatment, Second edition, 1984, Lea and Febiger, Philadelphia Chapters9 and 10 7. Hong, S., Ellis, G., and Hartman, K.: Calcifying Odontogenic Cyst, Oral Surgery Oral Medicine Oral Pathology, July 1991, pages 56-63 8. MacDonald-Jankowski, D. and Wu, P.: Cementoblastoma in Hong Kong Chinese, Oral Surgery, Oral Medicine, Oral Pathology, Vol. 73, June 1992, pages 760-763 9. Thawley, S. and Panje, W.: Comprehensive Management of Head and Neck Tumors, Volume 2, 1987, W.B. Saunders Co., Philadelphia, Chapter 57 10.Weber, A. etal: Diffuse Peripheral Odontogenic Fibroma:Report of 3 Cases, Journal of Oral Pathology and Medicine, Volume 24, July 1992, pages 82-84 ---------------------------------END-----------------------------------------