Presentation
Sciatica.
Patient Data
Intrathecal slightly hyperdense mass is seen at the L3 and L4 level without calcification or bony remodeling.
At the L3/L4 level, there is a well- defined intradural lesion that demonstrates homogeneous T2 hypointensity and intermediate T1 intensity. The cauda equina is displaced peripherally around this mass. Diffuse homogeneous enhancement post gadolinium administration. There are no peritumoral cysts or hemosiderin capping. The neural exit foramina are normal bilaterally throughout the lumbar levels.
Conclusion:
Although the shape is more typical of schwannoma or ependymoma, the T2 hypointensity favors meningioma.
Paraffin sections show a moderately cellular dural-based tumor. Tumor cells have moderately pleomorphic round and oval nuclei with vesicular chromatin and a moderate amount of clear cytoplasm containing varying amounts of glycogen.
Cell boundaries are poorly demarcated. There is a discernible syncytial arrangement of tumor cells in many areas. No mitotic figures or areas of necrosis are identified.
Immunohistochemistry shows strong membrane staining in tumor cells for epithelial membrane antigen (EMA) (not shown) and somatostatin receptor (SSR2). There also patchy moderate nuclear staining for progesterone receptor (PgR) (not shown).
The features are of clear cell meningioma (WHO Grade II). The topoisomerase labeling index is approximately 8%.
FINAL DIAGNOSIS:
Clear cell meningioma (WHO Grade II).
Case Discussion
This diagnosis was suggested preoperative on the basis of imaging alone which I think is pretty impressive as in this location one would usually favor myxopapillary ependymomas or schwannomas.