Keratocystic odontogenic tumour

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Odontogenic keratocyst
Keratocystic odontogenic tumour - 2 - very high mag.jpg
Micrograph of an odontogenic keratocyst. H&E stain.
Classification and external resources
ICD-10 D16.4 (Maxilla); D16.5 (mandible)
ICD-9-CM 213.0-213.1

An odontogenic keratocyst (also referred to occasionally as keratocystic odontogenic tumor, KCOT)[1] is a rare and benign but locally aggressive developmental cyst. It most often affects the posterior mandible. It most commonly presents in the third decade of life.[2]

It used to be called keratocystic odontogenic tumour (KCOT).[1][3]

In 2017, the new WHO classification of Head and Neck pathology re-classified OKC back into the cystic category. It is no longer considered a neoplasm as the evidence supporting that hypothesis (e.g. clonality) is considered insufficient. However, this is an area of hot debate within the head and neck pathology community, and some pathologists still regard OKC as a neoplasm despite the re-classification.

Signs and symptoms[edit]

Swelling is the most common presenting complaint; however, OKCs may be asymptomatic and found incidentally on dental X-rays.[4]


Malignant transformation to squamous cell carcinoma may occur, but is unusual.[5]


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


Sporadic (non-syndromic) and syndromic KCOTs are associated with mutations in the gene PTCH, which is part of the Hedgehog signaling pathway.[1][6]


Classic look to a keratocyctic odontogenic tumor in the right mandible in the place of a former wisdom tooth. Unicystic lesion growing along the bone.

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

Under the microscope, OKCs vaguely resemble keratinized squamous epithelium;[7] however, they lack rete ridges and often have an artifactual separation from their basement membrane.

On a CT scan, The radiodensity of a keratocystic odontogenic tumour is about 30 Hounsfield units, which is about the same as amelioblastomas. Yet, amelioblastomas show more bone expansion and seldom show high density areas.[8]

Differential diagnosis[edit]



  • Orthokeratocyst
  • Radicular cyst (particularly if the OKC is very inflamed)
  • Unicystic ameloblastoma


Massive keratocystic odontogenic tumour with impacted wisdom teeth superficial to lesion

As the condition is quite rare, opinions among experts about how to treat OKCs differ.

Treatment options:[1]

  • Wide (local) surgical excision.
  • Marsupialization - the surgical opening of the (OKC) 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).
  • Peripheral ostectomy after curettage and/or enucleation.
  • Simple excision.
  • Carnoy's solution - usually used in conjunction with excision.
  • Enucleation and cryotherapy [9]


  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. 
  2. ^ MacDonald-Jankowski, D S (2011). "Keratocystic odontogenic tumour: systematic review". Dentomaxillofacial Radiology. 40 (1): 1–23. ISSN 0250-832X. doi:10.1259/dmfr/29949053. 
  3. ^ Mateus GC, Lanza GH, de Moura PH, Marigo Hde A, Horta MC (November 2008). "Cell proliferation and apoptosis in keratocystic odontogenic tumors" (PDF). Med Oral Patol Oral Cir Bucal. 13 (11): E697–702. PMID 18978709. 
  4. ^ 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. doi:10.2334/josnusd.49.229. [dead link]
  5. ^ 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. 
  6. ^ PATCHED, DROSOPHILA, HOMOLOG OF, 1; PTCH1. OMIM. URL: Accessed on: December 25, 2008.
  7. ^ Thompson LDR. Head and neck pathology - (Foundations in diagnostic pathology). Goldblum JR, Ed.. Churchill Livingstone. 2006. ISBN 0-443-06960-3.
  8. ^ Ariji, Y; Morita, M; Katsumata, A; Sugita, Y; Naitoh, M; Goto, M; Izumi, M; Kise, Y; Shimozato, K; Kurita, K; Maeda, H; Ariji, E (2011). "Imaging features contributing to the diagnosis of ameloblastomas and keratocystic odontogenic tumours: logistic regression analysis". Dentomaxillofacial Radiology. 40 (3): 133–140. ISSN 0250-832X. doi:10.1259/dmfr/24726112. 
  9. ^ Schmidt BL, Pogrel MA (2001). "The use of enucleation and liquid nitrogen cryotherapy in the management of odontogenic keratocysts.". J Oral Maxillofac Surg. 59: 720–727. doi:10.1053/joms.2001.24278. 

Additional reading[edit]

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