PMC9282769_01
(a and b) He had originally undergone posterior laminectomy for lumbar canal stenosis at L3-L5 levels at another hospital 6 years before his first visit to us. There seemed no tumors at the L4 vertebral level. Several small tumors (arrowhead) had already existed in the cauda equina before laminectomy. (c and d) He had another tumor pointed out at the L4 vertebral level (arrow) 1 year after surgery. (e-h) Only the newly detected tumor (arrow) had gradually grown in size and had become symptomatic despite other small tumors (arrowhead) remaining the same in size.
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F1
Now at age 55, he newly presented with low back pain and numbness in the left L5 dermatome, and he was diagnosed with a L4 vertebral level cauda equina tumor (i.e., either newly developed or progressed) on MRI [Figures 1a-h arrow].
(a and b) The newly detected tumor (arrow) and several small tumors (arrowhead) were homogeneously enhanced on gadolinium-enhanced T1-weighted images. (c and d) The newly detected tumor was resected completely in the second surgery. The several small tumors (arrowhead) remained the same in size.
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F2
The lesion demonstrated the following classical MRI findings, such as a low-intensity mass on T1-weighted images, isointensity mass on T2-weighted images, and homogeneously enhancing mass on gadolinium T1-weighted images [Figures 2a and b arrow]. The tumor was totally resected en bloc with careful circumferential tumor dissection using intraoperative neurophysiological monitoring [Figures 2c, d and 3a-c].
(a) The tumor adhered to the irrelevant surrounding nerve roots. (b) Careful circumferential and subcapsular dissection allowed us to isolate the tumor from the irrelevant surrounding nerve roots. The nerve of origin was identified (arrowhead). (c) The tumor was resected en bloc by cutting the nerve of origin (arrowhead) following negative confirmation on direct nerve stimulation.
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F3
The tumor was totally resected en bloc with careful circumferential tumor dissection using intraoperative neurophysiological monitoring [Figures 2c, d and 3a-c].
(a and b) Histopathological analysis of the hematoxylin and eosin stained sections revealed coexistent hypercellular areas and hypocellular areas identified as Antoni A and B, respectively, which are indicative of schwannoma. (c) Ki-67 labeling index was 5-10% in hotspots, which is slightly higher than the normal range of schwannoma. (d) About 20% mosaic loss of SMARCB1 was observed. (a) Objective lens x5 and (b-d) objective lens x20.
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F4
The hematoxylin and eosin stained sections revealed coexistent hypercellular and hypocellular areas identified as Antoni A and B, respectively, consistent with the diagnosis of a schwannoma [Figures 4a and b]. Ki-67 labeling index was 5-10% in hotspots, which was slightly higher than the normal range of schwannomas [Figure 4c]. About 20% mosaic loss of SMARCB1 was observed [Figure 4d].