PMC10248439_01
A preoperative horizontal CT image of the lumbar spine (a) showed an abnormal density shadow (arrow) in the L5/S1 segment. A sagittal T2-weighted fat-suppressed MR image of the lumbar spine (b) showed that the right intervertebral foramen of the L5 segment is filled by tumor tissue (arrow) and the compressed nerve root. A horizontal T2-weighted fat-suppressed MR image of the lumbar spine (c) showed that the dumbbell-shaped tumor has an equal or slightly high signal (arrow) in the L5/S1 segment. The spinal cord deviated to the left, and the right foramen of L5/S1 widened. A horizontal T1-weighted fat-suppressed MR image (d) showed a slightly hypointense (arrow) tumor in the L5/S1 segment.
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F1
Pelvic computed tomography (CT) scanning revealed a mass with a heterogeneous signal arising through the foramina at the right-sided Lumbar 5 (L5) and Sacral 1 (S1) (Figure 1a). T2-weighted magnetic resonance imaging (MRI) showed a dumbbell-shaped mass filling the foramina with mixed areas of isointense and slightly hyperintense signals compared to skeletal muscle (Figures 1b-d). A frameshift mutation was detected [c.606del (p.D202Efs*7)] in exon 5 of the SMARCB1 gene, which was considered a "second-hit loss" (ADDL Figure 1).
Right sagittal CT scan of the lumbar spine image (a) showed the placement of pedicle screws at the L5/S1 segment and the fixation with titanium rods 1 week after the operation. The CT scan of the L5 segment image (b) showed that the pedicle screws are well positioned on both sides. The sagittal T2-weighted image of the lumbar spine MR (c) was normal 1 year after the operation, and the horizontal image showed a normal signal in the L5 intervertebral foramen (d).
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F2
Follow-up CT (Figures 2a, b) and MRI (Figures 2c, d) findings 1 week and 1 year after surgery showed no evident recurrence of the tumor.
Low-power view of diffuse growth of spindle tumor cells (a). Medium-power view of some tumor cells with clear cytoplasm and an epithelioid structure. Most of the specimens are obvious malignant tumors with active focal growth as well as mitotic images (b). The tumor was sporadically positive for the S100 protein by immunohistochemistry (c). Immunohistochemistry for Ki-67 was performed (d). Immunohistochemical staining showed the complete absence of SMARCB1/INI-1 (e), with retained expression in normal endothelial cells.
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F3
Immunohistochemistry revealed diffuse growth of spindle cells and polygonal cells visible in the low-power view (Figure 3a). Most of the specimens were malignant tumors with active focal growth and mitotic images (Figure 3b). The tumor was sporadically positive for the S100 protein by immunohistochemistry (Figure 3c). Immunohistochemistry for Ki-67 was performed (Figure 3d), and immunohistochemical staining showed complete deletion of SMARCB1/INI-1 (Figure 3e).