• Occurs in horses
  • Usually originate in maxillary sinus
  • Can extend to other sinuses
  • Some have dentigerous origin
  • Many are congenital
  • Histology:
    • Lined with pseudostratified epithelium overlying granulation tissue
    • Haemorrhage under the epithelium
    • Cyst walls contain bone spicules with osteoclastic and osteoblastic activity