Abstract
Osteoblastoma is a rare benign bone tumor, accounting for 1% of all bone tumors. It mainly occurs in the long bones, more rarely in the jaws. Osteoblastoma of the jaws mainly involves the mandible while nasosinusal involvement is very rare. The diameter of the tumor can grow to 10 cm. On X-ray, the tumor may appear as a well or poorly defined clear lesion, usually scattered with mineral patches. Recurrence rate is very low after surgical resection as well as the risk of malignant transformation. We report the case of a 13-year old female patient presenting with nasal obstruction evolving over the last 3 months associated with episodes of epistaxis and left blurred vision. Clinical examination showed voluminous nasal concha with polyploid mucosa filling all the left nasal fossa with left axial exophthalmos. CT scan of the facial massif showed left frontoethmoidal expansive process measuring 50*47*36 mm, spontaneously hypodense, heterogeneous, non enhanced after injection of the Contrast materials, responsible for destruction of the ethmoidal labyrinth, swelling of the bony walls with mass effect on the ipsilateral orbit. The suspected diagnosis was frontoethmoidal mucocele. Hence, the decision to perform endonasal surgery. Whitish thick liquid was collected by the cranial portion of the middle nasal concha sugesting infected mucocele. Resection of the middle nasal concha was performed. The histological examination showed osteoblastoma of the middle nasal concha . Outcome was marked by regression of the exophthalmos with no recurrence during 1-year follow up period.