Mandible & maxilla

Cysts of the jaw

Odontogenic keratocyst



Last author update: 26 March 2024
Last staff update: 26 March 2024

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PubMed Search: Odontogenic keratocyst

Kelly Magliocca, D.D.S., M.P.H.
Page views in 2024 to date: 9,189
Cite this page: Magliocca K. Odontogenic keratocyst. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/mandiblemaxillakeratocyst.html. Accessed April 15th, 2024.
Definition / general
  • Odontogenic keratocyst (OKC) is a developmental odontogenic cyst that is thought to arise from dental lamina and is characterized histologically by a thin, uniform parakeratinized stratified squamous epithelial lining with a hyperchromatic basal layer of cells
Essential features
Terminology
ICD coding
  • ICD-11: DA05.0 - developmental odontogenic cysts
Epidemiology
Sites
Pathophysiology
Etiology
  • Unknown
Clinical features
  • May be small or asymptomatic, incidentally detected on radiographs taken for unrelated reasons or for imaging to investigate delayed tooth eruption (Clin Oral Investig 2023;27:6951)
  • Large lesions may produce a painless bony expansion, can displace the involved tooth
  • If secondarily infected, may be associated with pain and swelling (Maxillofac Plast Reconstr Surg 2014;36:73)
Diagnosis
  • Histopathology supports the diagnosis
  • Lesion is intraosseous (within maxilla or mandible but may extend beyond bone borders into maxillary sinus, nasal floor or submucosa to mimic a peripheral lesion)
Radiology description
  • Radiology is essential to identify landmarks and the extent of disease in the preoperative and follow up setting
  • Panoramic radiograph (panorex), intraoral film or cross sectional imaging is useful depending on cyst location and size
  • Most commonly a well defined, unilocular radiolucency on Xray
  • May have sclerotic border (Dentomaxillofac Radiol 2018;47:20170288)
Radiology images

Contributed by Kelly Magliocca, D.D.S., M.P.H.
Sagittal CT anterior mandible

Sagittal CT anterior mandible

Axial CT left mandible

Axial CT left mandible

Axial CT anterior mandible

Axial CT anterior mandible

Coronal CT posterior mandible

Coronal CT posterior mandible


Coronal CT mandibular body

Coronal CT mandibular body

Cropped panorex left ramus

Cropped panorex left ramus

Cropped panorex body mandible

Cropped panorex body mandible

Prognostic factors
Case reports
Treatment
  • Surgical approach varies and factors for consideration include age, maturity, skeletal maturity, anatomic position, history of local recurrence, relative importance of tooth involved (if any), size of cyst, presence of additional pathology including but not limited to pathologic fracture, risk for fracture once removed, patient preference (risk versus benefits, acceptable risk of recurrence, cosmetic and functional considerations) (J Maxillofac Oral Surg 2024;23:145)
  • In small lesions, enucleation and curettage of the entire cyst is most common
Clinical images

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Well circumscribed mass

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Intraoral finding

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Less common maxillary lesion

Gross description
  • Surgical specimens usually consist of multiple, irregular fragments and may contain white or yellow keratinous debris (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2002;94:543)
  • Possible minute bone fragments
  • In cases of curettage type treatment, all mucosal, soft tissue and bone fragments should be submitted for histologic examination to definitively confirm the diagnosis
  • In resection cases, sampling surgically sectioned bone margins and relationship of cyst to bone and bone margins
  • Cyst lining is generally thin (0.1 - 0.2 cm in thickness), white and may have areas of folds and furrows but lacks papillary excrescences
  • Associated tooth received as specimen can be described grossly and supplemented with photographs where equipment is available
Gross images

Contributed by Kelly Magliocca, D.D.S., M.P.H.
Mandibular resection

Mandibular resection

Enucleation of mandibular lesion

Enucleation of mandibular lesion



Images hosted on other servers:
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Cystic lesion with thin smooth wall

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Massive KCOT

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Impacted maxillary third molar

Frozen section description
  • Uninflamed cysts show characteristic uniform epithelial lining, basal layer hyperchromatism and absent rete ridge formation
  • Histologic distortion is possible in the presence of inflammation
  • Inflamed cysts may show multilayered stratified squamous epithelium making it difficult to distinguish from unicystic ameloblastoma, luminal subtype or inflamed dentigerous cyst
  • Frozen section limitations include sampling bias, frozen section artifact and inability to perform immunohistochemistry such as BRAF V600e (J Oral Maxillofac Surg 2014;72:914)
Frozen section images

Contributed by Kelly Magliocca, D.D.S., M.P.H.
Overview

OKC overview

Hint of palisading

Hint of palisading

Epithelium

Epithelium

Basal palisading

Basal palisading

Abundant keratin

Abundant keratin

Cyst and keratin

Cyst and keratin

Microscopic (histologic) description
  • Uniform epithelial lining 6 - 8 cells thick lacking rete ridges
  • May have artifactual clefting between epithelium and underlying fibroconnective tissue
  • Epithelium is characterized by palisaded hyperchromatic basal cell layer composed of cuboidal to columnar cells
  • May have areas of budding growth from the basal cells
  • Luminal surface has wavy (corrugated) parakeratotic epithelial cells
  • Lumen may contain keratinaceous debris
  • Maxillary cysts can extend into maxillary sinus (Cureus 2022;14:e21002)
  • May have satellite cysts (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2001;91:328)
  • Rarely reported in association with psammomatoid calcifications (Oral Oncol 2023;147:106618)
Microscopic (histologic) images

Contributed by Kelly Magliocca, D.D.S., M.P.H. and Case #503
Solid OKC

Solid OKC

Macrocystic

Macrocystic OKC

Peaks at surface layer

Peaks at surface layer

Smooth surface layer

Smooth surface layer

Corrugated surface layer

Corrugated surface layer

Inflamed attenuated epithelium

Inflamed attenuated epithelium


Odontogenic keratocyst

Basal layer hyperchromatism

Squamous lined cyst

Areas of inflammation / irritation

Classic microscopic features

Virtual slides

Images hosted on other servers:
Odontogenic keratocyst

Odontogenic keratocyst

Cytology description
  • Isolated groups of keratinocytes with no nuclear atypia in a background of keratin debris (Cytopathology 2007;18:361)
  • Full thickness epithelial strips may demonstrate basal layer palisading
Cytology images

Contributed by Kartik Viswanathan, M.D., Ph.D. and Kelly Magliocca, D.D.S., M.P.H.
Touch prep

Touch prep

Imprint touch prep

Imprint touch prep

Positive stains
  • No specific immunohistochemistry required for odontogenic keratocyst
  • Squamous epithelium is expected to be immunoreactive for cytokeratin AE1 / AE3, p63 and p40
Negative stains
Molecular / cytogenetics description
  • Sonic hedgehog pathway alterations are common in odontogenic keratocysts, specifically PTCH1 inactivating mutations (Am J Surg Pathol 2020;44:553)
Videos

Odontogenic keratocyst - histopathology

Sample pathology report
  • Left mandible lesion, enucleation and curettage:
    • Odontogenic keratocyst
Differential diagnosis
  • Orthokeratinized odontogenic cyst:
    • Similar name, however, this cyst is unrelated to odontogenic keratocyst with limited risk for recurrence and no association with basal cell nevus syndrome
    • Uniform stratified squamous epithelium lining with prominent granular layer
    • Cuboidal to flat basal layer, no basal palisading
    • No surface corrugation
    • Thick luminal lamellated keratin (onion skin-like)
  • Calcifying odontogenic cyst:
    • Cystic basaloid odontogenic epithelium with palisading basal cells, loosely arranged suprabasal epithelial cells resembling stellate reticulum, variable numbers of ghost cells in suprabasilar epithelium
    • Dystrophic calcifications
    • Paucicellular, eosinophilic partially calcified material (dentinoid)
    • Beta catenin nuclear positive
  • Unicystic ameloblastoma:
    • Palisading of columnar basal cells with hyperchromatic nuclei
    • Generally exhibits reverse polarization of nuclei (away from basement membrane)
    • Stellate reticulum is often less distinct
    • Mandibular lesions often have BRAF p.V600E mutations (Int J Oral Maxillofac Surg 2024;53:122)
  • Dentigerous cyst:
    • Fibrous to fibromyxoid connective tissue
    • No rete ridges, flat interface
    • Lining epithelium, 2 - 4 layers of cuboidal epithelium, devoid of superficial keratinization
    • Occasional mucous cells; rare ciliated cells
    • Occasional dystrophic calcifications
    • Odontogenic epithelial rests, small, inactive appearing within fibrous wall
  • Radicular / periapical cyst:
    • Radicular cyst (RC) is an inflammatory odontogenic cyst associated with the root of a nonvital tooth
    • Surfaced by nonkeratinized stratified squamous epithelium
    • Often characterized by an arcading pattern
    • Cyst wall is composed of inflamed fibrous tissue, may have foamy histiocytes
  • Carcinoma cuniculatum:
      Cuniculatum overview

      Cuniculatum overview

      Resembles OKC

      Resembles OKC

      Cyst-like cuniculatum

      Cyst-like cuniculatum


    • Sampling of the more deeply positioned cystic burrows of carcinoma cuniculatum bears resemblance to OKC in some cases
    • Very well differentiated subtype of carcinoma
    • Prominent intercellular bridges, minimal atypia and rare mitotic figures
    • Can have keratin cysts
    • May have superficial vacuolated clear cells
    • Often associated with inflammatory infiltrate that may obscure tumor stroma boundary
    • Intraepithelial abscess formation is common
Board review style question #1

Which feature is most characteristic of odontogenic keratocyst?

  1. Granular cell layer present
  2. Infiltrative lesion with mitotic activity
  3. Stellate reticulum-like suprabasal layer
  4. Well defined layer of palisading hyperchromatic basal cells without reverse polarity
Board review style answer #1
D. Well defined layer of palisading hyperchromatic basal cells without reverse polarity. Odontogenic keratocyst has a well defined layer of palisading hyperchromatic basal cells without reverse polarity. Answer C is incorrect because the stellate reticulum-like suprabasal layer is common in ameloblastoma and can also be seen in calcifying odontogenic cyst. Answer B is incorrect because odontogenic keratocyst is a benign lesion; an infiltrative lesion with mitotic activity is concerning for malignancy. Answer A is incorrect because if a granular cell layer is present, consider the possibility of an orthokeratinized odontogenic cyst.

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Reference: Odontogenic keratocyst
Board review style question #2
Which of the following sites is most commonly involved by odontogenic keratocyst?

  1. Anterior mandible
  2. Anterior maxilla
  3. Maxillary sinus
  4. Posterior mandible
Board review style answer #2
D. Posterior mandible. The posterior mandible is the most common site of involvement for odontogenic keratocyst. Answer B is incorrect because a cystic lesion in the anterior maxilla, specifically in the midline, could represent a nasopalatine duct cyst. Answer A is incorrect because odontogenic keratocyst occurs in the anterior mandible but this is not the most common site. Answer C is incorrect because odontogenic keratocyst occurs in the maxilla with extension into the maxillary sinus but this is not the most common site of occurrence.

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Reference: Odontogenic keratocyst
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