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29 yo, F

An expansile mixed radiolucent/radiopaque lesion in the posterior maxilla


Gross Findings

The specimen consisted of solid mass fragments.


Microscopic Findings

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Final Diagnosis:


  • ≤ 1% of OT
  • No gender predilection
  • Any age, with a predilection for third to sixth decade of life (mean:40)
  • The mandible is affected twice as often as the maxilla



  • Local surgical removal with tumour-free margin
  • Recurrence: 15%


Take-Home Message

  • A Congo red stain is useful to confirm the presence of odontogenic ameloblastic associated protein, a substance histologically identical to amyloid
  • Due to the rarity of these lesions, pathologists should be aware of the ‘pseudo pleomorphism’ of the tumour cells.
  • The Ki-67 index is low in benign lesions, reported as less than 2%. In a case of malignant transformation, the Ki-67 rose to 42% in tumor cells.