Hyperkeratosis and atypical proliferation appearing in the lining epithelium of a radicular cyst. Report of a case.

It is widely accepted that radicular cysts (apical periodontal cysts) are commonly lined with stratified squamous epithelium without keratin formation. However, we identified a case of maxillary radicular cyst with remarkable keratinization and atypical proliferation of the lining epithelium among the 207 radicular cyst cases seen at our department. Histopathological and clinical findings of these cysts were reviewed.