[Nasoethmoidal psammomatoid cemento-ossifiying fibroma with intraorbital extension].

INTRODUCTION: Psammomatoid cemento-ossifying fibroma (PCOF) is a rare benign fibro-osseous lesion. It affects the maxilla, the nasal cavity, paranasal sinuses, and the ethmoid. It is slow-growing, progressive, and benign but it can be locally extended and mimic a malignant tumor. OBSERVATION: We report the unusual case of a 36-year-old woman with a nasal and ethmoid PCOF with orbital and endocranial extension. The tumor was revealed by exophthalmia and nasal obstruction. The diagnosis was proven histologicaly on biopsies. The treatment was transfacial surgery. There was no recurrence 1 year later. DISCUSSION: Intraorbital and endocranial extension of PCOF are rare aggressive behaviours. Histologically, the differential diagnosis is difficult between fibrous dysplasia or psammomatoid meningioma. Complete surgical excision is necessary to prevent recurrence.