Large Odontogenic Fibroma of the Mandible Mimicking Malignancy in an Adolescent Male: Diagnosis Unveiled on Histopathology

Background: Odontogenic fibroma is a very rare benign tumour of the jaw with an overall incidence of less than 1% of all odontogenic tumours. It can either be unilocular or multilocular cystic tumour with a significant overlap between clinical and radiological findings amongst different odontogenic tumours of oral cavity. Case report: We present a case of an odontogenic fibroma of mandible in a 14-year old boy, which was clinically suspected to be osteosarcoma with radiological differentials of odontogenic myxoma and ossifying fibroma. Histopathological examination showed a tumour composed of variably cellular fibroblastic stroma with bits of lamellar bone showing osteoblastic rimming. Interspersed strands of bland odontogenic epithelium and multinucleated giant cells were noted. There was no mitosis or atypia. Final diagnosis of odontogenic fibroma was rendered on histopathologic examination of the biopsy specimen. Conclusion: This case report highlights the role of histopathological examination in diagnosing odontogenic fibroma, which can easily be missed due to clinical and radiological similarities with other benign and malignant entities.