Sinonasal ossifying fibroma

Case contributed by Mostafa Elfeky
Diagnosis almost certain


Right nasal obstruction.

Patient Data

Age: 17 years
Gender: Female

An expansile osseous lesion is noted filling the right nasal cavity with some cystic changes. It is mainly epicentered upon the right ethmoid air cells. It exerts mass effect with bowing of the nasal septum and the medial wall of the right orbit narrowing the orbital apex.

The right maxillary sinus is opacified with retained secretions, mostly due to obstruction of the ostiomeatal complex by the right sinonasal mass.


The right nasal lesion shows deep low T2 signal on MRI and mild diffuse post Gadolinium enhancement. Smaller zones of cystic nature are noted with bright T2 signal and no postcontrast enhancement.

Superiorly, the mass exerts expansile thinning of the anterior skull base. No osseous interruptions. No intracranial extensions.

Laterally, it exerts marked expansile bowing of the lamina papyracea, smoothly encroaching on the orbital contents near the apex. Still, no optic nerve compression. Also noted obstruction of the maxillary antrum drainage with filling by thickened mucosa and retained secretions.

Case Discussion

The right sinonasal expansile mixed osseous/cystic lesion filling the right nasal cavity, proven histopathologically as an ossifying fibroma (pathology report not available).​ It exerts local mass effect with orbital apex compression by bulging lamina papyracea.

It is one of the bone-related benign lesions of the odontogenic apparatus. See the article 2005 WHO histological classification of odontogenic tumors for more other related tumors.

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