Ethmoid Osteoblastoma: A Case Report and Pooled Analysis of Cases.

Osteoblastoma is a typically noncancerous bone tumor commonly found in the spine and long bones of the arms and legs. It is exceedingly rare for this tumor to occur in the paranasal sinuses. We present a case of osteoblastoma in a 13-year-old boy affecting the ethmoid sinus, which manifested as exophthalmos. A computed tomography scan revealed an expansive lesion in the right ethmoid sinus, causing compression and displacement of the orbital contents to the right. The lesion exhibited a mix of ground glass opacity and dense bone. On magnetic resonance imaging, the less dense areas of the tumor showed strong enhancement, while the densely sclerotic regions appeared as signal voids on all imaging sequences. A combined transorbital and transnasal approach was performed to remove the tumor. Histologically, the tumor consisted expansile growth surrounded by a sclerotic rim of inter-anastomosing trabeculae of woven bone set within loose edematous fibrovascular stroma. This case highlights the unusual occurrence of osteoblastoma in the ethmoid sinus, a location seldom associated with this type of tumor, and adds to the existing literature on this topic and offers a new surgical approach to managing this entity.