Presentation
Gradual bilateral leg weakness.
Patient Data
The whole of the thoracic cord from the level of the C7/T1 disc through to the conus is slightly expanded and displays abnormal signal within the grey matter. The central canal is slightly dilated up to a maximum of 3 mm in diameter in the mid thoracic cord. No abnormal vessels are detected. Post contrast views show slight, diffuse contrast enhancement, maximal in the conus and lower thoracic cord. The conus terminates opposite L2.
This patient's symptoms had been gradual and progressive. There was no history of preceding infection or illness, and CSF was bland. The lesion did not resolve on follow up imaging and a biopsy of the conus confirmed a diffuse WHO II astrocytoma.
Enhancement is usually present but can be subtle and careful side by side comparison of pre and post contrast images may be required to detect faint diffuse enhancement.
Note how at the L5/S1 level the apparent region of intradural enhancement (blue arrow) has a similar appearance on pre contrast and is attributable to bulging epidural fat (yellow arrow).
Case Discussion
This case illustrates how diffuse a diffuse spinal cord astrocytoma can be, and one can easily understand why they are difficult to diagnose without the aid of MRI.