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, 1^st & 2^nd  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: 3^rd to 5^th 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.