Benign Schwannoma in the Sphenoid Sinus: two cases report

Reprint requests to: Dr. Yu-Chang Lee Department of Radiology E-Da Hospital/I-Shou University. No.1, Yi Da Road, Jiau-shu Tsuen, Yan-Chau, Kaohsiung 824, Taiwan, R.O.C. Schwannomas are common neoplasms in the head and neck region, but of these tumors only less than 4% was found in sinonasal location in the reported literature. Most of the reported cases are found in the maxillary or ethmoid sinuses. Schwannomas involving the sphenoid sinus may further elude the init ial diagnosis because of their close proximity to the skull base. Hereby we report two cases of sphenoid sinus schwannomas with diagnostic diff iculties on imaging studies which may be confused with other more common skull base tumors. Schwannomas are common benign neoplasms which arise from the peripheral nerve sheath and embryonically f rom the neuroectoderm. About 25-45% of all schwannomas arised in the head and neck region and of these only less than 4% was located at sinonasal cavity in the reported literature. Radiologists may encounter preoperative diagnostic diff iculties of schwannoma involving paranasal cavities due to their rarity, varied clinical symptoms and imaging features. For example, a sphenoid sinus schwannoma sometimes could be confused with other more common skull base tumor such as clival chordoma, chondrosarcoma and plasmacytoma. The differential diagnosis should be carefully laid out since they have different prognosis and treatment plan to be executed. Thus, we report two cases of sphenoid sinus schwannomas with discussion of related skull base tumors and reviewed literatures.