Mandible & maxilla
Odontogenic cysts
Orthokeratinized odontogenic cyst

Editor-in-Chief: Debra Zynger, M.D.
Nasir Ud Din, M.B.B.S.

Minor changes: 14 September 2020

Copyright: 2020, PathologyOutlines.com, Inc.

PubMed Search: Orthokeratinized odontogenic cyst[TIAB]

Nasir Ud Din, M.B.B.S.
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Cite this page: Ud Din N. Orthokeratinized odontogenic cyst. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/mandiblemaxillaorthokeratinized.html. Accessed September 30th, 2020.
Definition / general
  • A benign developmental odontogenic cyst, mostly unilocular, with a fibrous tissue wall lined predominantly or entirely by orthokeratinized stratified squamous epithelium
Essential features
  • Cystic bone lesion in mandible or maxilla with compatible radiological features
  • Cyst has orthokeratinized stratified squamous epithelial lining
  • Cyst wall is fibrous and uninflamed
Terminology
  • Previously called orthokeratinized variant of odontogenic keratocyst (OKC) (no longer recommended to use by WHO)
Epidemiology
Sites
  • Most commonly (90.16%) involves mandible (mandibular molar and ramus) (Arch Pathol Lab Med 2010;134:271)
  • Maxilla involvement in 9.84% of cases
  • Multiple and bilateral cases have been reported
Pathophysiology
  • Thought to originate from dental lamina and its remnants; developmental in nature
Etiology
  • Unknown
Clinical features
Diagnosis
  • Requires correlation of orthopantomogram (OPG) findings with histological features
Radiology description
Radiology images

Contributed by Nasir Ud Din, M.B.B.S.
OOC right mandible OOC right mandible

Right mandible

Prognostic factors
Case reports
Treatment
  • Enucleation
Clinical images

Images hosted on other servers:

Extraoral swelling

Obliterated buccal sulcus

Gross description
  • If an intact cyst is enucleated:
    • Keratinous material filled cystic lesion
    • Usually unilocular but may be multilocular
    • Fibrous cyst membrane may envelope crown of molar tooth (Int J Appl Basic Med Res 2016;6:297)
  • In curated specimens:
    • Multiple flattened, irregular, soft to firm and pearl white to gray-white to tan-brown cystic tissue fragments
Gross images

Images hosted on other servers:

Cyst lining envelops crown of tooth

Frozen section description
  • Frozen section is seldom done for odontogenic cysts
Microscopic (histologic) description
  • Noninflamed fibrous cyst wall lined by thin uniform stratified squamous epithelium
  • Prominent granular layer
  • Thick luminal lamellated keratin (onion skin-like)
  • Chevroning of lamellated keratin in some cases
  • Cuboidal to flat basal layer
  • No surface corrugation or basal palisading is seen
  • Focal parakeratinized epithelium in case of inflammation
  • Reference: Arch Pathol Lab Med 2010;134:271
Microscopic (histologic) images

Contributed by Nasir Ud Din, M.B.B.S.
Cyst wall fragments Cyst wall fragments

Cyst wall fragments

Cyst wall lumen

Cyst wall lumen

Cyst wall fragments

Cyst lining

Cyst wall fragments

Cyst lining

Cyst wall fragments

Cyst lining

Positive stains
Videos

Clinical features, radiology and histopathology

Sample pathology report
  • Right posterior mandible, enucleation:
    • Orthokeratinized odontogenic cyst (see comment)
    • Comment: Histologic and radiologic features support the diagnosis.
Differential diagnosis
  • Odontogenic keratocyst (OKC):
    • Peak incidence in second and third decades
    • Mostly solitary, unilocular, well demarcated radiolucency
    • Multiple cysts in 10% of cases
    • Much more common
    • Associated with nevoid basal cell carcinoma syndrome
    • Associated with aggressive behavior (28 - 30% recurrence)
    • Thin uniform lining of parakeratinized squamous epithelium
    • Corrugated layer of parakeratin on its luminal surface
    • Palisaded layer of columnar basal cells (reverse polarity)
    • No keratohyalin granules
    • Lumen may contain keratinaceous debris
    • Frequent separation of the epithelial lining from underlying connective tissue
    • Dental lamina rests and microcysts occasionally present in capsule wall
  • Dentigerous cyst (DC):
    • Radiologically similar as both are associated with unerupted molar tooth of mandible
    • Much more common
    • Peak incidence in second to fourth decades of life
    • Noninflamed lining is thin; 2 - 3 layers of regular nonkeratinizing stratified squamous epithelium
    • Inflamed lining is hyperplastic with elongated rete ridges
    • Mucus metaplasia and cilia are also seen
Board review style question #1

The most important histological feature to differentiate orthokeratinized odontogenic cyst (see image) from odontogenic keratocyst is

  1. Absence of parakeratin
  2. Orthokeratinized squamous epithelium with prominent granular layer
  3. Presence of luminal lamellated keratin
  4. Thick stratified squamous epithelium
  5. Uninflamed fibrous cyst wall
Board review answer #1
B. Orthokeratinized squamous epithelium with prominent granular layer

Comment Here

Reference: Orthokeratinized odontogenic cyst
Board review style question #2
Which of the following cysts most closely mimics orthokeratinized odontogenic cyst radiologically?

  1. Calcifying epithelial odontogenic cyst
  2. Dentigerous cyst
  3. Lateral periodontal cyst
  4. Odontogenic keratocyst
  5. Radicular cyst
Board review answer #2
B. Dentigerous cyst

Comment Here

Reference: Orthokeratinized odontogenic cyst
Board review style question #3
The most important histological feature to differentiate orthokeratinized odontogenic cyst from dentigerous cyst is

  1. Absence of basal palisading
  2. Elongated rete ridges
  3. Orthokeratinzed granular squamous epithelium
  4. Thick stratified squamous epithelium
  5. Uninflamed fibrous wall
Board review answer #3
C. Orthokeratinzed granular squamous epithelium

Comment Here

Reference: Orthokeratinized odontogenic cyst

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