So-called hybrid central odontogenic fibroma/central giant cell lesion of the jaws. A report on seven additional cases, including an example in a patient with cherubism, and hypotheses on the pathogenesis.

Abstract

Central odontogenic fibroma (COF) is characterized by poor to cellular fibroblastic proliferation and a variable odontogenic epithelial (OE) component. Central giant cell lesions (CGCL) are osteolytic fibroblastic proliferations characterized by osteoclast-like multinucleated giant cells (MGC). Rare examples of hybrid COF/CGCL have been described. Two pathogenetic theories prevail based on clinicopathologic characteristics. One regards the CGCL component as reactive to the COF, while the other regards the CGCL as inductive of a COF-like proliferation. The possibility of colliding tumors seems unlikely. Seven patients with hCOF/CGCL, among them one with cherubism, were studied. Immunohistochemistry for cytokeratin 19 was applied to better appreciate the epithelial component. Six patients were males and one female and their age ranged from 15 to 73 years old. All lesions occurred in the premolars and molars of the mandible and presented as radiolucencies with primarily well-delineated borders. All patients underwent surgical excision and recurrences have not been reported to this date in 6 out of 7 patients (mean follow-up 60.6+/-36.25 months). The COF component predominated in 3 cases and the CGCL component in 3. Zones of collagen fibers featuring a whorling pattern and containing multiple nests of OE were present. In four cases there were hyalinized deposits in OE, while some foci of MGC contained few OE. Gender predilection in our series is in contrast with previously published reports. However, when all previously reported cases are reviewed there is still female predilection. The predominant site, as previously reported, is the tooth-bearing areas of the posterior mandible. This is the first report of hCOF/CGCL in cherubism. The pathogenesis of hCOF/CGCG remains obscure and molecular interactions would be of interest to be investigated.