Keratocystic odontogenic tumour
Classification and external resources
Micrograph of a keratocystic odontogenic tumour. H&E stain.
ICD-10	K09.0
ICD-9	526.0

A keratocystic odontogenic tumour (also keratocystic odontogenic tumor), abbreviated KCOT,^[1] is a rare and benign but locally aggressive developmental cystic neoplasm. It most often affects the posterior mandible.

It was previously called odontogenic keratocyst and abbreviated OKC.^[1][2]

[edit] Diagnosis

Micrograph of a keratocystic odontogenic tumour showing the characteristic features (see text).

The definitive diagnosis is by histologic analysis, i.e. excision and examination under the microscope.

Under the microscope, KCOTs vaguely resemble keratinized squamous epithelium;^[3] however, they

1. lack rete ridges and
2. often have an artifactual separation from their basement membrane.

[edit] Etiology

KCOTs are thought to arise from the dental lamina and associated with impacted teeth. Multiple odontogenic keratocysts are a feature of nevoid basal cell carcinoma syndrome.

[edit] Genetics

Sporadic (non-syndromic) and syndromic KCOTs are associated with mutations in the gene PTCH, which is part of the Hedgehog signaling pathway.^[1][4]

[edit] Symptoms

Swelling is the most common presenting complaint; however, KCOTs may be asymptomatic and found incidentally on dental X-rays.^[5]

[edit] Differential diagnosis

• Odontogenic cyst (histologically)
• Dentigerous cyst
• Ameloblastoma (radiologically)

[edit] Malignant transformation

Malignant transformation to squamous cell carcinoma may occur, but is unusual.^[6]

[edit] Treatment

As the entity is quite rare, opinions among experts about how to treat KCOTs differ.

Treatment options:^[1]

• Wide (local) surgical excision.
• Marsupialization - the surgical opening of the (KCOT) cavity and a creation of a marsupial-like pouch, so that the cavity is in contact with the outside for an extended period, e.g. three months.
• Curettage (simple excision & scrape-out of cavity).
• Simple excision.
• Carnoy's solution - usually used in conjunction with excision.

[edit] References

1. ^ ^{a b c d} Madras J, Lapointe H (March 2008). "Keratocystic odontogenic tumour: reclassification of the odontogenic keratocyst from cyst to tumour". J Can Dent Assoc 74 (2): 165–165h. PMID 18353202. http://www.cda-adc.ca/jcda/vol-74/issue-2/165.html. 
2. ^ Mateus GC, Lanza GH, de Moura PH, Marigo Hde A, Horta MC (November 2008). "Cell proliferation and apoptosis in keratocystic odontogenic tumors". Med Oral Patol Oral Cir Bucal 13 (11): E697–702. PMID 18978709. http://www.medicinaoral.com/medoralfree01/v13i11/medoralv13i11p697.pdf. 
3. ^ Thompson LDR. Head and neck pathology - (Foundations in diagnostic pathology). Goldblum JR, Ed.. Churchill Livingstone. 2006. ISBN 0-443-06960-3.
4. ^ PATCHED, DROSOPHILA, HOMOLOG OF, 1; PTCH1. OMIM. URL: http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=601309. Accessed on: December 25, 2008.
5. ^ Habibi A, Saghravanian N, Habibi M, Mellati E, Habibi M (September 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. http://joi.jlc.jst.go.jp/JST.JSTAGE/josnusd/49.229?from=PubMed. 
6. ^ Piloni MJ, Keszler A, Itoiz ME (2005). "Agnor as a marker of malignant transformation in odontogenic keratocysts". Acta Odontol Latinoam 18 (1): 37–42. PMID 16302459. 

[edit] Additional Reading

• Kahn, Michael A. Basic Oral and Maxillofacial Pathology. Volume 1. 2001.

[edit] External links

• Odontogenic keratocyst - pathconsultddx.com.