PMC9990762_01
Sagittal (a-1 and 2) and axial (b) views of three-dimensional heavily T2-weighted imaging (3D-hT2WI) demonstrating a tumor (yellow arrow) in the cauda equina. (c) 3D T1-weighted images (3D-T1WI) showing the isointense lesion (yellow arrow) of the cauda equina and a high intensity lesion (dotted arrow) of the terminal filum. Sagittal (d) and axial (e) views of 3D-T1WI demonstrating the tumor enhanced with gadolinium (yellow arrow). (f-1-5) Serial coronal views of 3D-hT2WI delineating that the tumor (yellow arrow) is located in the dorsal nerve roots (yellow arrowheads) that enter the dural sac at the left L3-L4 and L4-L5 intervertebral space. Normally-positioned dorsal root ganglions (white arrowheads) are observed at the root sleeves as local bulging. The level of each vertebral body is indicated by a dashed line. (g) 3D reconstructions of computed tomography image revealing spina bifida below S2 and abnormal fusion of the sacral lamina of L5-S2.
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F1
MRI demonstrated a small tumor in the cauda equina that had isosignal intensity to the spinal cord on three-dimensional T1-weighted imaging (3D-T1WI) and 3D heavily T2WI (3D-hT2WI) and was slightly enhanced with gadolinium [Figures 1a-e]. L3 and L4, presumed from the entry point of the root into the dural sac [Figure 1f]. Local bulging was observed at the root sleeves of L3 and L4, indicating the presence of normally-positioned DRG. A 3D reconstructions of computed tomography image revealed spina bifida below S2 and abnormal fusion of the lamina of L5-S2 [Figure 1g].
(a-1 and 2) Microscopic view of the surgery for the cauda equina tumor. Laminotomy at L3 revealed a tumor (a-1; blanket length of 10 mm). (a-2) A few nerve roots running over the lesion surface and extending caudally (arrows); some thinner nerve roots ending at the tumor surface (arrow heads). (b) Coronal view of 3D-hT2WI after the second surgery demonstrated that the cauda equina tumor (arrow) remained unchanged and the untethering of the cord was achieved (dotted arrow). (c-e) Histopathological findings of the resected parts of the tumor stained with hematoxylin and eosin (H & E; c), and immunostained with S-100 (d) and Ki-67 (e). (c) The resected section consisted of ganglion cells (GC) and peripheral nerve fibers. The periphery of the ganglion cells is immunopositive for S-100 (d), a few of which are immunopositive for Ki-67 (arrows; e).
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F2
The tumor was surrounded by nerve roots; a few normal-appearing nerve roots ran over the surface of the tumor and extended caudally, while some thinner nerve roots ended at the tumor surface [Figure 2a-2]. MRI performed after the second surgery revealed that the untethering of the cord was achieved and the cauda equina tumor remained unchanged [Figure 2b]. Histopathologically, the resected section consisted of ganglion cells and peripheral nerve fibers [Figures 2c-e].