Odontogenic fibroma, including amyloid and ossifying variants.

Sixty-five cases of odontogenic fibroma (OdonF) are herein presented having been segregated into peripheral, extra bony tumors (n = 40) and tumors arising in bone or centrally (n = 25). All cases were characterized microscopically by a fibrous proliferation that varied within and between cases in cellularity and collagen fibril diameter, with intermixed odontogenic epithelial islands and cords. All central lesions presented as well demarcated radiolucencies and resorption of contiguous tooth roots was a common finding. These intraosseous lesions were of the WHO type; the so-called nonWHO type was excluded as all lesions with this diagnosis were devoid of an epithelial component and could be reclassified as other soft tissue fibrogenic tumors. Neither the central tumors nor the peripheral lesions recurred following enucleation/curettage, with a mean follow-up of 4 and 3.4 years respectively. Three distinct microscopic variations were encountered in this series: (1) two cases of OdonF with giant cell reaction, (2) two instances of OdonF with ossifying fibroma; and (3) four instances of OdonF with odontogenic ameloblast-associated protein (ODAM), an amyloid-like protein found deposited adjacent to epithelial cords plus CD1a+/S-100+ Langerhans dendritic cells entwined around the epithelial element. A single instance of the odontogenic fibroma-like hamartoma/enamel hypoplasia syndrome has been included in this series.