Cemento-ossifying fibroma is a relatively rare, benign, non-odontogenic tumour of the jaws, regarded as a subdivision of fibro-osseous lesions. The usual age of occurrence is between 20 and 40 years.

The female:

male ratio is 5:1, usual site being the posterior mandible. The aim of this report to present the clinical and radiological features and management of a 32-year-old female Libyan patient who presented with an asymptomatic giant swelling of three years' duration in the left mandible, the diagnosis of which was confirmed by histopathology. Cemento-ossifying fibroma (COF) is a benign, asymptomatic lesion of the jaws characterized by the production of well-demarcated bone of slow growth. It typically affects females aged between 20 and 40 years, in the premolar and molar area, causing a painless swelling, of slow, expansile growth. The periodontal ligament contains both bone and cementum. The pathogenesis of extraosseous COF, where there is no periodontal tissue, as suggested by Cakir and Karadayi, originates in embryonic nests and the ectopic periodontal membrane, as suggested by Brademann et al. in their cytogenetic studies. Depending on the stage of maturation, cemento-ossifying fibroma may range from radiolucent, through mixed, to completely radio-opaque. Histopathologically, it appears as well-circumscribed, occasionally encapsulated with various amounts of bony trabecular/cementum formation in a fibrous stroma... (AU)