Peripheral odontogenic fibroma. Report of 5 cases.

The peripheral odontogenic fibroma (WHO type) is a relatively rare, benign, unencapsulated, exophytic gingival mass of fibrous connective tissue. Odontogenic epithelium is found within the gingival mass, but usually appears to play a minor role when compared to the fibrous component. According to the present concept, cases reported in the literature under the terms "odontogenic gingival epithelial harmartoma" "hamartoma of the dental lamina" and "peripheral ameloblastic fibrodentinoma" are actually examples of peripheral odontogenic fibroma. Review of the literature revealed only 30 acceptable cases that fit the present concept of peripheral odontogenic fibroma. Because of the paucity of reported cases, the histomorphological spectrum and the clinical features of this lesion have not yet been fully established. This article presents five new cases of peripheral odontogenic fibroma. The connective tissue ranged from markedly cellular to relatively acellular well collagenized. Islands and strands of epithelium were present in all five cases: in four they were scanty and in one abundant. A matrix of mineralized material was present in four cases. The peripheral odontogenic fibroma must be differentiated histologically from peripheral ossifying fibroma, which is a reactive lesion, and from the peripheral ameloblastoma and the calcifying epithelial odontogenic tumour.