Frontal sinus cementifying ossifying fibroma.

Cementifying ossifying fibroma is a fibro-osseous lesion which produces cementum. Cementifying ossifying fibroma is a mesodermal, non-odontogenic tumor of ectopic multipotential periodontal membrane blast cells. Although, it is a benign bone tumor, it has an aggressive destructive behavior in patients under 20 years of age with high tendency for recurrence. Cementifying ossifying fibroma can be recognized microscopically by the presence of cementicles. This is a case of frontal sinus cementifying ossifying fibroma presenting with proptosis in a 39-year-old male.