Hybrid central odontogenic fibroma with giant cell granuloma-like component: case report and review of literature.

Central odontogenic fibroma (COF) is a rare benign ectomesenchymal tumor of the jaws. Only 12 cases of COF with giant cell granuloma (GCG)-like lesion have been reported in the English literature. Here, we present a new case of COF epithelium rich type with a GCG-like component. Radiographically, this lesion presented as a well defined unilocular radiolucency in the body of the mandible. Histologically, the lesion showed a unique confluence of odontogenic epithelial rests with multinucleated giant cells (MNGCs) in a highly cellular fibrous connective tissue stroma, with osteoid and cementoid deposits. A distinct area showed the typical histological picture of each component separately. Immunohistochemical staining with pancytokeratin (CK) highlighted the odontogenic epithelial component merging with the GCG component throughout most of the lesion. The significance of GCG-like areas within COF is the reported increased risk of recurrence following curettage, possibly necessitating more aggressive therapy.