Keratocystic odontogenic tumor (KCOT)


  • 2-3rd decade

Common site

  • 70 – 80% mandible especially 3rd molar and ascending ramus region


  • Rests of dental lamina


  • PCTH tumor suppressor mutation
  • High epithelial proliferation (Ki67+ve)
  • Apoptosis evasion by increased Bcl2
  • Over expression of interface proteins:


  • Painless
  • Slow growing expansile intraosseous mass
  • Discovered on routine x-ray
  • Grow in anterior – posterior direction. Reach large sizes without gross bony expansion

Clinical subtypes

  • Solitary lesion
  • Multiple lesions
  • Syndrome associated lesion: Gorlin Goltz syndrome
    • Therefore do full body check up


  • Cyst wall:
    • Fibrous
    • Thin and corrugated/ folded
    • Contains daughter/satellite cyst
  • Epithelial lining:
    • Flat basement membrane
    • Hyaline/Rushton bodies
    • Keratinized squamous epithelium
    • Lack rete pegs
    • Thin and even thickness, < 10 cells thick
  • Lumen:
    • Straw colored fluid (keratin)
  • Basal cells Ki67 and Bcl2 positive – shows high mitotic figures


  • Unilocular/multilocular radiolucency, some with impacted teeth
  • Well circumscribed radiolucency with radiopaque margins


  • Aspirational biopsy:
    • Greasy fluid
    • Pale in color
    • Contains keratotic squames

Differential diagnosis


  • Wide surgical excision to avoid recurrence (significant recurrence rates)
  • Marsupialization
  • Curettage
  • Enucleation with application of Carnoy’s solution

Reasons for increased recurrence rate

  1. Thin fragile lining – difficult to enucleate intact
  2. Finger like cystic extensions into cancellous bone
  3. Presence of satellite/daughter cyst in cystic wall/capsule
  4. Formation of additional keratocysts from other rests of dental lamina
  5. Inferior standards of surgical treatment
  6. Possibly a neoplasm

Reasons it can be considered a neoplasm

  1. High recurrence rate
  2. Fast growth/aggressive behaviour
  3. Can invade adjacent tissues
  4. Possible malignant transformation
  5. Associated with mutated PTCH suppressor gene


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