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Saturday, July 23, 2011

Oral Pathology Lectue Note- Odontogenic Tumours(Part 2)

ADENOMATOID ODONTOGENIC TUMOUR
  • Earlier, believed to be a variant of Ameloblastoma with glandular elements and was referred to as ADENOAMELOBLASTOMA.
  • Now believed to be a separate entity and thought to arise from odontogenic epithelial cells.



CLINICAL FEATURES: -
  • Age incidence: Young individuals, 1st & 2nd  decades.
  • Sex incidence: More in females, twice more.
  • Site predilection: Anterior aspect of maxilla.

SIGNS & SYMPTOMS:-

  • Small, asymptomatic lesion.
  • Discovered accidentally during routine dental X-ray examination to ascertain cause for unerupted tooth.
  • Larger lesions cause jaw expansion




RADIOLOGICAL FEATURES:

  • Typical well defined unilocular ‘lucency attached to an impacted / unerupted tooth, usually canine (FOLLICULAR VARIETY).
  • ‘Lucency extends past cervical region & must be distinguished from dentigerous cyst.
  • Extrafollicular – well defined ‘lucency not related to unerupted tooth.
  • In both cases, ‘lucency may contain snowflake like radio opacities.

DIFFERENTIAL DIAGNOSIS: -
Radiographic appearance can suggest following lesions for provisional diagnosis -
                1. Unicystic ameloblastoma
                2. CEOT
                3. COC
                                                                                                               
HISTOLOGICAL FEATURES: -

  • Lesion is composed of spindle shaped epithelial cells that form sheets, strands or whorls in a scanty stroma.
  • Rosette like structures may show a central space which may be empty or contain some eosinophilic  amyloid like material.
  • Tubular duct like spaces are also seen which show a central space surrounded by reversely polarized cells.

 CALCIFYING EPITHELIAL ODONTOGENIC TUMOUR
  • Rare tumor, accounts for > 1% of all odontogenic tumors.
  • Although odontogenic in origin, its histogenesis is uncertain.
  • Tumor cells strongly resemble stratum intermedium of dental organ.

CLINICAL FEATURES: -
Age incidence: 3rd to 5th decades.
Sex incidence: Equal.
Site predilection: 75% cases occur in posterior mandible.
Signs & symptoms: Asymptomatic, slowly  growing swelling.

RADIOLOGICAL FEATURES:












  • Commonly appears as a well defined, scalloped, uni/multilocular ‘lucency, usually associated with an impacted tooth.
  • Lesion may also show presence of scattered radiopaque material within the ‘lucency.

DIFFERENTIAL DIAGNOSIS: -
  1. Odontogenic cysts like dentigerous, OKC,  etc.
  2. Odontogenic tumors like Ameloblastoma,  etc.
  3. Other bony lesion like Central giant cell granuloma, Aneurismal bone cyst etc.
HISTOLOGICAL FEATURES: -

  • Tumor shows discrete islands / sheets of polyhedral epithelial cells in a fibrous stroma.
  • Nuclei show lot of size variation, even giant nuclei can be seen.
  • Tumor islands also enclose large areas of eosinophilic, amorphous, amyloid like material
  • The cell outlines of tumor epithelial cells are distinct and intercellular bridges may be noted.
  • The amyloid like material usually  calcifies to form concentric rings (LEISEGANG RINGS).

ODONTOMA
  • Most common odontogenic tumor.
  • Considered hamartomas, rather than neoplasm.
  • In a fully developed odontoma, mainly enamel and dentin along with variable amounts of pulp and cementum are seen.

CLASSIFICATION: -
Odontomas are further sub classified into
                                - COMPOUND ODONTOMA
                                - COMPLEX ODONTOMA
Both occur with equal frequency.
Compound – composed of multiple, small, tooth like structures.
Complex – composed of conglomerate mass of enamel and dentin with no anatomic relationship to tooth.
CLINICAL FEATURES : -
  • Age incidence: First 2 decades.
  • Sex incidence: None.
  • Site predilection: Anterior maxilla.

SIGNS & SYMPTOMS:
  • Mostly asymptomatic, small, seldom exceeding the size of tooth missing in the region.
  • Larger lesions may cause jaw expansion.                                                                                                               

ODONTOMA (COMPOUND)



Gross pathological specimen showing a mass of more than 20 tooth like malformed structures.









ODONTOMA (COMPOUND)
RADIOLOGICAL FEATURES:-

  • This type is composed of multiple, small tooth like structures.
  • The entire mass appears surrounded by a radiolucent rim.
  • An unerupted tooth is usually associated with both types of  odontomes which impedes normal eruption of the tooth.

ODONTOMA (COMPLEX)
RADIOLOGICAL FEATURES:

  • Complex odontoma comprises of a single conglomerate mass of tooth like material.
  • It bears no anatomic resemblance to any tooth.
  • Appears as a ‘opaque mass surrounded by a narrow ‘lucent rim.

ODONTOMA (COMPOUND)
HISTOLOGICAL FEATURES: -

  • Microscopically, it shows discrete tooth like denticles in a fibrous stroma.
  • Being a decalcified specimen, enamel appears as spaces around normal looking dentin and pulp which bear normal anatomic relationship to each other.

ODONTOMA (COMPLEX)
HISTOLOGICAL FEATURES:-

  • Consist of largely tubular dentin enclosing clefts / hollow circular spaces that contained enamel prior to decalcification.
  • Thin layer of cementum sometimes may be present at the periphery.

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