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FIG 1. ;t1Case 1: Disk cyst.
A, Sagittal T1-weighted image (right paramedian). A small L3-L4 herniated disk is seen (black arrowhead). Just below the herniated disk, a cystic mass is depicted with homogeneous low signal intensity.
B, Sagittal T2-weighted image (right paramedian). The cystic mass delineates homogeneous high intensity. The small L3-L4 herniated disk is just above the cyst.
C, Axial T1-weighted image at the cranial portion of the L4 level. Signal intensity of the cystic mass is equal to that of CSF.
D, Axial T2-weighted image at the cranial portion of the L4 level (same level as that shown in C). The cystic lesion displaces the dural sac dorsomedially. Erosion of the posterior margin of the L4 vertebral body (small arrows) is seen.
E, Enhanced sagittal T1-weighted image. The cyst shows rim enhancement.
F, Enhanced axial T1-weighted image (same level as that shown in C) shows rim enhancement of the cyst.
G, CT scan at L3-L4 after diskography. The contrast material is present in the L3-L4 disk (arrows).
H, CT scan at L4 after diskography. The contrast material spills out of the disk space and accumulates at the right dorsal aspect of the upper L4 body level (white arrows), corresponding to the cyst seen on the MR image.
I, Histologic section of the cyst wall (hematoxylin and eosin; original magnification, x 25). The cyst wall is composed of fibrous connective tissue without synovial cells or hemosiderin. Vascular proliferation (arrows) and a few lymphocytes (black arrowheads) are seen.
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