Male patient, aged 10 years, referred to the Oral and Maxillofacial Surgery Department of the Piñero Hospital to be assessed for an increase in volume in the right mandibular angle region of two weeks' evolution; with no medical history of interest. The swelling was not painful on palpation and there was no report of paraesthesia.

Intraoral examination revealed bulging of the vestibular and lingual table of the lower jaw. The teeth were healthy and without mobility; the mucosa appeared normal.

Radiographically, a radiolucent, unilocular lesion with sclerotic borders was observed. Root resorption of tooth 37 was also evident.

The biopsy result was fibroma ossificans, so the lesion was scheduled for enucleation under general anaesthesia. The pathological anatomy confirmed the result of ossifying fibroma.

The last clinical-radiographic control was performed at eight months, with a good evolution and radiographic evidence of bone neoformation and increased thickness of the mandibular basal. The patient remains under follow-up to rule out recurrence of the tumour...