66 yo male complaining of a tumour of the palate.

CT scan shows extension to the sinus.

Proposed Diagnosis:

Dentinogenic ghost cell tumour (WHO)

• Tumour infiltrating the surrounding tissue.
• Sheets and rounded islands of odontogenic epithelium in a mature connective tissue.
• Epithelium resembles that of an ameloblastome: follicular, with rare plexiform areas, and keratinization.
• Minor cysts are noted in the epithelial islands.
  Characteristic features (distinguishing from ameloblastome):
• Transformation of epithelial cells into ghost cells,
• Extrusion in the connective tissue evokes a foreign body reaction. Some undergo calcification.
• Formation of dysplastic dentin in minute amounts.
• Immunohistochemistry: CK5/6 +, and CK7 +, with negative clusters of basaloïd cells.
• Prognosis: aggressive lesion, to be treated like an ameloblastome.

(Ref. WHO Blue Book, Head and Neck)