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 histology 101
Teeth develop from a combination of:
- Epithelium (downward growth).
- Mesenchyme.
Identifying stuff
Pulp:
- Paucicellular.
- Pale staining.
Enamel:
- Hyperchromatic (dark purple).
- "Fish scale" appearance.
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. (???)
Specific entities
Odontoma
General
- Usually diagnosed clinically.
- Benign.
- Most common odontogenic tumour - considered to be a hamartoma.[1]
- Etiology unknown.[2]
- Typically first two decades of life.
Classification:[1]
- Compound odontoma - tooth-like structure.
- Complex odontoma - disorganized mass of odontogenic tissues.
Microscopic
Features:[1]
- Dentin.
- Cementum.
- Pulpal tissue.
- Enamel - has a "fish-scale" appearance.
- Usually lost during decalcificiation.
Images:
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
General
- 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.
- Keratocystic odontogenic tumour - keratinized epithelium.
Image:
Keratocystic odontogenic tumour
- Abbreviated KOT.
- Previously known as odontogenic keratocyst, abbreviated OKC.[3]
General
- May be associated with nevoid basal cell carcinoma syndrome.
Clinical
Features:[4]
- Most common presentation: swelling.
Gross
- Location: usually mandible.
- May mimic ameloblastoma radiologically.
Microscopic
Features: [5]
- Stratified epithelium resembling squamous epithelium - typically 8-10 cell layers thick - with relatively uniform thickness ("ribbon-like appearance").
- Artefactual separation of epithelium from the basement membrane.
- Parakeratosis (keratinized cells with nuclei) - key feature.
- Palisaded basal cell layer.
- Lacks rete ridges.
DDx:
- Odontogenic cyst.
- Orthokeratinized odontogenic cyst (has orthokeratosis instead of parakeratosis).
- Orthokeratosis = keratinized cells no nuclei; parakeratosis = keratinized cell with nuclei.
- Orthokeratinized odontogenic cyst (has orthokeratosis instead of parakeratosis).
Images:
- KOT - intermed. mag. (WC).
- KOT - very high mag. (WC).
- KOT - another case - intermed. mag. (WC)
- KOT - poor quality (WC).
- KOT - showing artefactual clefting - poor quality (WC).
Ameloblastoma
General
- Osteous lesion.
- Usually mandible.[6]
- In a review of 3677 cases, the mandible-to-maxilla ratio was 5 to 1.[7]
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:[8]
- Stellate reticulum - star-shaped cells, found in a developing tooth.
- 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 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):
Images:
- www:
- WC:
Morphology
- Not prognostic.
Morphologic variants:
- Follicular ameloblastoma (classic appearance).
- Plexiform ameloblastoma (does not have prominent palisading).
- Acanthomatous ameloblastoma.
- Desmoplastic ameloblastoma.
- Basaloid ameloblastoma.
Adenomatoid odontogenic tumour
General
- Paedatric population.
Microscopic
Features:
- Palisaded nuclei.
- Whorled epithelium.
Notes:
- No stellate reticulum.
DDx:
Image:
Ameloblastic fibroma
General
- Paedatric population.
Microscopic
Features:
- Palisaded nuclei.
- Fibrous stroma.
Notes:
- No stellate reticulum.
DDx:
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
- ↑ 1.0 1.1 1.2 1.3 Nelson, BL.; Thompson, LD. (Dec 2010). "Compound odontoma.". Head Neck Pathol 4 (4): 290-1. doi:10.1007/s12105-010-0186-2. PMID 20533004.
- ↑ Yadav, M.; Godge, P.; Meghana, SM.; Kulkarni, SR. (Apr 2012). "Compound odontoma.". Contemp Clin Dent 3 (Suppl 1): S13-5. doi:10.4103/0976-237X.95095. PMID 22629054.
- ↑ 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.waent.org/archives/2010/Vol3-2/20100618-ameloblastoma/jaw-tumor.htm. Accessed on: 30 November 2011.
- ↑ Reichart, PA.; Philipsen, HP.; Sonner, S. (Mar 1995). "Ameloblastoma: biological profile of 3677 cases.". Eur J Cancer B Oral Oncol 31B (2): 86-99. PMID 7633291.
- ↑ URL: http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675%2806%2970616-7. Accessed on: March 9, 2010.