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Friday, July 22, 2011

Oral Pathology Lectue Note- Odontogenic Tumours(Part 1)

  • Odontogenic tumors comprise a complex group of lesions with varied histopathological and clinical features.
  • Some tumors are true neoplasms, while some are hamartomas (developmental malformations).
  • Some are composed only of odontogenic epithelium, while many are mixed i.e. both epithelium and mesenchyme, while some are composed only of mesenchyme



TUMORS OF ODONTOGENIC EPITHELIUM: -
1. Ameloblastoma
2. Calcifying epithelial odontogenic tumor
3. Adenomatoid odontogenic tumor
4. Squamous odontogenic tumor
            5. Clear cell odontogenic tumor

TUMORS OF ODONTOGENIC EPITHELIUM & MESENCHYME WITH / WITHOUT DENTAL HARD TISSUE FORMATION: -
           1. Ameloblastic fibroma & Ameloblastic fibrosarcoma.
           2. Ameloblastic fibro odontoma
           3. Odontoameloblastoma
           4. Odontoma – Compound & Complex

TUMORS OF ODONTOGENIC MESENCHYME WITH / WITHOUT DENTAL HARD TISSUE FORMATION: -
          1. Odontogenic fibroma
          2. Odontogenic myxoma
          3. Cementoblastoma
          4. Granular cell odontogenic tumor

AMELOBLASTOMA
Most common odontogenic neoplasm, derived from odontogenic epithelium.
Slowly growing, locally aggressive, benign neoplasm.
Occurs in 3 different types with differing clinical, radiological and histological features.
                1. CONVENTIONAL / MULTICYSTIC
                2. UNICYSTIC
                3. PERIPHERAL

AMELOBLASTOMA - CONVENTIONAL
CLINICAL FEATURES: -
  • Age incidence: 3rd & 4th decades.
  • Sex incidence: Slightly more in males.
  • Site predilection: 80% ameloblastomas occur in posterior  mandible, followed by maxillary molar         region.


Signs & symptoms: -

   










  • Slowly growing, painless, hard bony swelling or expansion of jaw.
  • Thinning of cortical plates produces “Egg shell crackling”.
  • Other symptoms – Tooth mobility  root resorption and paresthesia if inferior alveolar nerve is affected. 



RADIOLOGICAL FEATURES: -
  • Typically rounded, well defined multilocular radiolucency with scalloped margins.
  • When loculations are large, the appearance is called as “SOAP BUBBLE” appearance.
  • When loculations are smaller, the appearance is called “HONEY COMBED” appearance.
  • Buccal & lingual cortical plates are expanded.
  • Roots of adjacent teeth displaced / resorbed.
  • As it spreads through medullary spaces, radiographic margins are not accurate indication of bone involvement.









DIFFERENTIAL DIAGNOSIS: -
  ODONTOGENIC KERATOCYST
  FIBROUS DYSPLASIA
  OSSIFYING FIBROMA
  CENTRAL GIANT CELL GRANULOMA

HISTOPATHOLOGICAL FEATURES: -
Many subtypes are seen.
1.       FOLLICULAR
2.       PLEXIFORM
3.       ACANTHOMATOUS
4.       GRANULAR CELL
5.       DESMOPLASTIC
6.       BASAL CELL TYPE
7.       CLEAR CELL Type

AMELOBLASTOMA (FOLLICULAR)

  • Islands of epithelium resemble dental organ surrounded by mature connective stroma.
  • Individual follicles show central mass of stellate reticulum like cells surrounded by a single peripheral layer of ameloblast like cells.
  • Nuclei of peripheral cells are reversely polarized.
  • Within the islands, cyst formation is common.

                                               
AMELOBLASTOMA (PLEXIFORM)

  • Instead of islands, long, anastomosing cords and occasional sheets of epithelial cells bounded by columnar / cuboidal cells.
  • Cells within cords are more loosely arranged than peripheral cells.
  • Supporting stroma is loose and vascular.
  • Cyst formation occurs, not inside follicles, but in surrounding stroma.

                                               
AMELOBLASTOMA (ACANTHOMATOUS)

  • Central area of follicles show extensive squamous metaplasia, often associated with keratin formation.
  • DOEAS NOT INDICATE A MORE AGGRESSIVE COURSE OF TUMOR.
  • Can be confused with squamous cell carcinoma.


AMELOBLASTOMA (GRANULAR CELL)

  • Follicles / sheets of cells show granular cell change.
  • These cells have abundant cytoplasm filled with eosinophilic granules.
  • Seen in younger persons and appears to be more aggressive clinically.


AMELOBLASTOMA (DESMOPLASTIC)

  • This variant is composed of small islands / cords of odontogenic epithelial cells surrounded by a dense, collagenized stroma.
  • Peripheral ameloblast like cells are missing / inconspicuous around the islands / cords.
  • Occurs in anterior jaw and radiologically looks like a fibro-osseous lesion due to mixed opacity & lucency.

                                               
AMELOBLASTOMA (BASAL CELL)

  • Least common type.
  • Composed of nests / sheets of hyperchromatic basaloid cells.
  • No stellate reticulum present centrally and peripheral cells tend to be cuboidal rather than tall columnar.

TREATMENT: -
  • Can vary from simple enucleation to curettage to en bloc resection.
  • As lesion spreads through medullary spaces, simple enucleation can leave islands of tumor within the jaws, leading to recurrence.
  • Marginal resection is the optimal method.
  • Rarely can undergo malignant transformation.

                                                                                                               
UNICYSTIC AMELOBLASTOMA
Controversy, whether it arises de novo or as neoplastic transformation of odontogenic cyst lining.
CLINICAL FEATURES: -
  • Age incidence: Young individuals.
  • Sex incidence: males.
  • Site predilection: 90% cases occur in post  mandible.
  • Signs & Symptoms: Asymptomatic swelling of jaws. Many lesions contain a tooth inside.

                                                                                               
RADIOLOGICAL FEATURES: -
  • Typically seen as well defined, unilocular ‘lucency, many times surrounding the neck of impacted 38 or 48 – impossible to distinguish from dentigerous cyst.
  • Occasionally, may be seen unassociated with teeth – then they nay be diagnosed as OKC or a radicular cyst.

DIFFERENTIAL DIAGNOSIS: -
        Odontogenic cysts like – Dentigerous, OKC, radicular etc.
        Odontogenic tumors like – Ameloblastoma, AOT, CEOT etc.
                                                                                                               
HISTOPATHOLOGICAL FEATURES: -
Three variants are recognized.
                1. LUMINAL UNICYSTIC
                2. INTRALUMINAL UNICYSTIC
                3. MURAL UNICYSTIC
                                                                                                               
UNICYSTIC - LUMINAL

  • Tumor is confined to luminal surface of cyst.
  • Seen as fibrous cyst wall with lining comprised totally / partially of ameloblastic epithelium, showing a basal layer of columnar / cuboidal reversely polarized cells.
  • Overlying epithelial cells are loosely adhesive, resembling the stellate reticulum of dental organ.

                                               
UNICYSTIC - INTRALUMINAL

  • This variant shows the tumor from cyst lining protruding into the lumen of cyst.
  • Intraluminal projections resemble plexiform ameloblastoma in most cases, though not always.                                       

UNICYSTIC - MURAL

In this type, the fibrous wall of the cyst is infiltrated with typical follicular / plexiform ameloblastoma.
Believed to be more aggressive than other two variants.
                               
AMELOBLASTOMA (PERIPHERAL)

  • Typically presents as non ulcerated, sessile / pedunculated gingival mass.
  • Must be differentiated from other more common gingival swellings.


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