E2357. Greater Sphenoid Wing: Differential Diagnosis, Pearls and Pitfalls
University of California San Francisco
Boston Children's Hospital
The greater wing of the sphenoid is an important component of the skull base and when involved by a meningioma, characteristic imaging findings include a sunburst pattern of osseous hyperostosis and surrounding plaque-like enhancement that involves the lateral orbit, the dura of the middle cranial fossa and adjacent temporalis muscle. Not all masses within the greater sphenoid wing however are meningiomas. It is important to recognize that there is a differential diagnosis for lesions in this location which is dependent on the age of the patient and the specific imaging features on CT and MRI. This exhibit reviews the pearls and pitfalls of lesions occurring in this unique anatomic location.
Educational Goals / Teaching Points
1) Review the anatomy of the greater sphenoid wing and adjacent structures.
2) Review the differential diagnosis of lesions of the greater sphenoid wing including meningioma, primary bone/cartilaginous tumors, metastatic disease, myeloma, lymphoproliferative tumors, vascular malformations, fibro-osseous and developmental lesions.
3) CT, MR and Nuclear Medicine findings of these conditions will be discussed- highlighting overlapping and distinguishing imaging features.
Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
The greater wing of the sphenoid forms the anterior margin of the middle cranial fossa, lateral border of the orbit and articulates with the squamosal portion of the temporal bone posteriorly and frontal bone anteriorly. The sphenoparietal sinus courses along the posterior margin of the greater sphenoid wing. Several important skull base foramina are present within the sphenoid bone which allow the transmission of important neurovascular structures between the brain and orbit/face.
Meningiomas are common lesions to occur within the greater sphenoid wing. Meningiomas are known to cause hyperostosis of the adjacent skull reported to occur in up to 44% of cases. However, when meningiomas occur within the greater sphenoid wing localized hyperostosis is seen in 90% of cases.1 Based on histopathologic analysis, this characteristic feature within the GSW is felt to be related to tumor infiltration of the bone, which is not typically seen elsewhere in the skull.1 Other neoplastic and non-neoplastic lesions can mimic an intraosseous meningioma, particularly if they too result in hyperostosis. Primary bone/cartilaginous tumors, metastatic disease, myeloma, lymphoproliferative tumors, vascular malformations, fibro-osseous and developmental lesions will be discussed with a focus on distinguishing imaging features.
Meningiomas of the greater wing of the sphenoid demonstrate a characteristic imaging appearance on CT and MR. Understanding the pearls and pitfalls for lesions of the greater sphenoid wing will allow radiologists to be more confident diagnosing tumors and tumor mimics to guide therapeutic management.