Peripheral odontogenic fibroma.

Peripheral odontogenic fibroma (WHO type) is an uncommon lesion of the gingiva; 18 well-documented cases have been published. It is considered to be the extraosseous counterpart of the central odontogenic fibroma. Because of the paucity of reported cases, the full histomorphologic spectrum of this lesion has not yet been established. This article presents nine cases of peripheral odontogenic fibroma that illustrate the variety of its histopathologic findings. The connective tissue ranged from loose (almost myxomatous) to markedly cellular to relatively acellular and well-collagenized. Islands and/or strands of odontogenic epithelium were present in all lesions. Matrix of mineralized material was present in three cases, and juxtaepithelial hyalinization was seen in one case. To avoid the introduction of additional diagnostic terms, we suggest that all these lesions be considered a spectrum of the peripheral odontogenic fibroma (WHO type). We also suggest that the term WHO type be used to distinguish peripheral odontogenic fibromas from the peripheral ossifying fibroma with which they have often been confused.