Odontogenic tumours and cysts
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This article covers odontogenic tumours and cysts, which is a subset of oral pathology and can be grouped under the heading of head and neck pathology.
The general topic of head and neck pathology is covered in the head and neck pathology and head and neck cytopathology articles.
Tooth histiology 101
Teeth develop from a combination of:
- Epithelium (downward growth).
- Mesenchyme.
Enamel 101
- Arises from reduced enamel epithelium.
Reduced enamel epithelium
Microscopic
Features:
- Bilayered epithelium consisting of:
- Cuboidal/columnar cells with:
- Moderate eosinophilic cytoplasm.
- Round (slightly irregular) centrally place nuclei.
- Cuboidal/columnar cells with:
Notes:
- Transforms into squamous epithelium. (???)
Compound odontome
General
- Usually diagnosed clinically.
- Benign.
Microscopic
Features:
- ???
Radicular cyst
- AKA periapical cyst.
Clinical
- Non-vital tooth - key feature.
- The tooth that has lost its nerve.
Microscopic
Features:
- Squamous epithelium - always non-keratinized.
- +/-Giant cells.
- +/-Cholesterol clefts.
DDx:
- Dentigerous cyst (history is the key to differentiate).
Notes:
- Keratinized epithelium: think keratocytic odontogenic tumour.
Dentigerous cyst
Clinical
- Unerupted tooth - usually wisdom teeth.
- Young adults.
Gross
- Lesion at crown of tooth.
Microscopic
Features:
- Squamous epithelium - always non-keratinized.
- +/-Giant cells.
- +/-Cholesterol clefts.
DDx:
- Radicular cyst (history is the key to differentiate).
Notes:
- Keratinized epithelium: think keratocytic odontogenic tumour.
Keratocystic odontogenic tumour
General
- Used to be known as odontogenic keratocyst.[1]
- May be associated with nevoid basal cell carcinoma syndrome.
Clinical
Features:[2]
- Most common presentation: swelling.
- Location: usually mandible.
- May mimic ameloblastoma radiologically.
Microscopic
Features: [3]
- Stratified epithelium resembling squamous epithelium -- but:
- Lacks rete ridges.
- Artefactual separation of epithelium from the basement membrane.
DDx:
- Odontogenic cyst.
Images:
Ameloblastoma
General
- Osteous lesion.
Classification
Location:
- Intra-osseous.
- Locally aggressive.
- Peripheral.
- Benign.
Subclassification of intra-osseous type
Histology:
- Solid/multicystic.
- More commonly reoccur.
- Unicystic.
- Unlikely to reoccur.
- Classically found in younger individuals.
Microscopic
Features:[4]
- Stellate reticulum - star-shaped cells, found in a developing tooth.[5]
- Tall columnar cells.
- Palisaded nuclei with reverse polarization.
- Reverse polarization of nuclei = nuclei distant from the basement membrane/nuclei at pole opposite of basement membrane.
- Palisaded nuclei = picket fence appearance; columnar-shaped nuclei with long axis aligned perpendicular to the basement membrane -- key feature.
- Subnuclear vacuolization.
- Palisaded nuclei with reverse polarization.
- +/-Giant cells.
- +/-Subepithelial hyalinization (eosinophilic acellular amorphous material).
- Seen deep to the basement membrane.
- Variable morphology (see below - morphology).
DDx (nuclear palisading):
- Adenomatoid odontogenic tumour.
- Ameloblastic fibroma.
Images:
=Morphology
- Not prognostic.
Morphologic variants:
- Follicular ameloblastoma (classic appearance).
- Plexiform ameloblastoma (does not have prominent pallisading).
- Acanthomatous ameloblastoma.
- Desmoplastic ameloblastoma.
- Basaloid ameloblastoma.
Adenomatoid odontogenic tumour
General
- Paedatric population.
Microscopic
Features:
- Palisaded nuclei.
- Whorled epithelium.
Notes:
- No stellate reticulum.
DDx: Ameloblastoma.
Ameloblastic fibroma
General
- Paedatric population.
Microscopic
Features:
- Palisaded nuclei.
- Fibrous stroma.
Notes:
- No stellate reticulum.
DDx: Ameloblastoma.
Odontogenic myxoma
General
- Benign tumour of mesenchymal origin.
- Often reoccurs.
- Radiologic DDx includes ameloblastoma.
Gross
- Gelatinous mass.
Microscopic
Features:
- Paucicellular lesion with pale staining.
See also
References
- ↑ Madras, J.; Lapointe, H. (Mar 2008). "Keratocystic odontogenic tumour: reclassification of the odontogenic keratocyst from cyst to tumour.". J Can Dent Assoc 74 (2): 165-165h. PMID 18353202.
- ↑ Habibi, A.; Saghravanian, N.; Habibi, M.; Mellati, E.; Habibi, M. (Sep 2007). "Keratocystic odontogenic tumor: a 10-year retrospective study of 83 cases in an Iranian population.". J Oral Sci 49 (3): 229-35. PMID 17928730.
- ↑ Thompson LDR. Head and neck pathology - (Foundations in diagnostic pathology). Goldblum JR, Ed.. Churchill Livingstone. 2006. ISBN 0-443-06960-3.
- ↑ URL: http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675%2806%2970616-7. Accessed on: March 9, 2010.
- ↑ URL: http://en.wikipedia.org/wiki/Stellate_reticulum. Accessed on: March 9, 2010.