Introduction: Benign diseases of the sphenoid sinus can be classified as intrinsic, originating from the mucosa and sinus bone walls, and extrinsic, arising from adjacent structures. We analyze the CT features of both intrinsic and extrinsic benign sphenoid conditions and their diagnostic role and impact on treatment planning.
Material and methods: We reviewed the CT scans of 75 patients with benign sphenoid sinus conditions from our 1993-96 series. The conditions were diagnosed at histology of the surgical specimen or from clinical findings and patient's history. Both axial scans, parallel to the orbitomeatal line, and coronal scans, perpendicular to the hard palate, were always acquired. The matrix was 512 x 512 and the FOV was appropriate. The different diseases were diagnosed based on the CT features of normal sinus bone walls or, conversely, wall thickening/thinning, focal erosions or bone destruction. The density of intra- and extrasinusal tissue and its contrast enhancement, intratissutal calcifications or bone fragments and changes in the sphenoethmoid recess were also studied.
Results: Sinus bone walls were normal in 41/75 cases, focal/diffuse thinning was found in 12, focal interruption in 7 and thickening in 10. Intra- and perisinusal tissue with soft-tissue density was detected in 66/71 cases, with high density in 4 and low density in 1 case. Contrast enhancement of the pathologic tissue was found in 15 cases. Sphenoethmoid obliteration was demonstrated in 29 cases, with enlargement in 5 and reduction in 5.
Discussion: Benign diseases of the sphenoid sinus are an uncommon finding. They are mainly due to chronic or recurrent inflammatory diseases, frequently associated with pansinusal involvement. Sphenoid sinus involvement can also be found in pathologic conditions originating from adjacent structures. We conclude that the accurate study of the intra- and extrasinusal soft tissue and bone walls permits to hypothesize the nature of a benign pathologic process, which has an impact on treatment planning. CT can be considered the technique of choice in the study of the sphenoid region.