Presentation
Sciatica.
Patient Data
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There are bilateral L5 pars defects, without anterolisthesis. Bony alignment is normal. No canal or exit foraminal narrowing. No nerve impingement is evident.
At the L5 and S1 level, there is the impression of increased density within the thecal cul de sac.
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A well defined intradural ovoid lesion is centered within the distal lumbosacral canal. Lesion fills the canal space from the L5-S2 levels. The lesion is confined to the canal without extension into the adjacent exit foramen. It is difficult to determine if the mass arises from a specific nerve root. The lesion has heterogeneous signal characteristics, predominately low signal on T2 weighted images and isointense to CSF on T1 weighted images. On STIR weighted imaging the lesion is predominantly of moderate signal intensity with areas of low signal within which may represent blood products.
Unfortunately, contrast has not been given. No evidence of leptomeningeal deposition elsewhere within the thoracic or lumbar spine however non-contrast imaging is less sensitive for detection of this.
Case Discussion
The patient went on to have a resection.
Histology
Paraffin sections show fragments of a moderately hypercellular tumor composed of cells with uniform round and oval nuclei with finely granular chromatin and delicate processes. These are arranged in diffuse sheets and perivascular pseudo-rosettes. No mitotic figures are seen and there is no vascular endothelial cell hyperplasia and no necrosis. Myxoid-mucinous material is noted in some of the pseudo-rosettes interposed between the central blood vessel and the surrounding corona of tumor cells.
Tumor cells show strong immunostaining for GFAP. Weak staining for epithelial membrane antigen (EMA) is noted in some pseudo-rosettes. The Ki-67/MIB-1 labeling index is <1%.
FINAL DIAGNOSIS: myxopapillary ependymoma (WHO Grade I)
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