A clinicopathologic study on central odontogenic fibroma: with special reference to amyloid variant

The aim of this study was to clarify the clinicopathologic features of central odontogenic fibroma (OF), especially the amyloid variant, and to discuss its association with the Langerhans cell variant of calcifying epithelial odontogenic tumor (CEOT).

The clinicopathologic features and immunophenotypes of 17 OFs, including 6 amyloid variants, were analyzed. The Langerhans cell variant of CEOT is reviewed, and its relationship with OF is discussed.

Most OFs (13 of 17) were located at the anterior region of the jaws, often with root resorption. The amyloid variant exhibited the typical clinicopathologic features of OFs, characterized by dispersed small epithelial nests embedded in a fibrous stroma. Immunohistochemically, the epithelial component in all central OFs, including the amyloid variants, exhibited dispersed staining for CK10/13 but was negative for CK7 and CK8/18. Langerhans cells were positive for S-100 and Langerin in the epithelium of OFs, including the amyloid variants.

The amyloid variant of OF is a rare benign tumor exhibiting the typical clinicopathologic features of conventional OFs and should not be diagnosed as CEOT even in the presence of amyloid deposits. Previously reported cases described as "Langerhans cell variant of CEOT" should be classified as the "amyloid variant of OF," given that it shares features more in common with OFs than with CEOTs.