PMC8077366_01
Contrast-enhanced lumbosacral MRI. 3-T MRI was performed in axial T2FRFSE, sagittal T1FSE, T2FRFSE, and T2 Fat Sat, and MR neurography with 3D STIR. a, b Axial T2-weighted sequence demonstrating a cystic mass (orange arrows) in foraminal zone L5-S1 along the passage of the ischial nerve to the left ischial sulcus at the level of the left lateral presacral space. c, d Enhanced T1-weighted sequence demonstrating peripheral rim contrast enhancement (orange arrows) consistent with an encapsulated cystic mass. e-j Coronal T2-weighted sequence (e, f) and 3D STIR MR neurography (g) (green arrows), as well as sagittal T2-weighted sequence (h, i) and MR neurography (j) showing a long mass in the sciatic nerve in the foraminal zone and the left sulcus (red arrows) with a lesion length of +-13.90 cm and a maximal diameter of +-1.91 cm.
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F1
In this case, MR neurography clearly showed the location of the mass in the sciatic nerve to the left ischial groove (Fig. 1).
During the operation, a tumor was seen originating from the sciatic nerve sheath.
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F2
Two months later, the patient underwent surgery to resect the tumor and rescue the involved nerve roots (Fig. 2).
a Histopathological examination (H&E, x40) showing a rich cell neoplasm, with bland round-to-spindle-shaped and wavy nuclei, loosely arranged in sheets; the margin of the tumor is lined by a well-defined fibrous capsule (black arrow). b Area of microcyst formation, suggesting schwannoma (H&E, x400).
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F3
A histopathological examination was performed (Fig. 3).
a MRI evaluation after surgery. b Axial coronal T2-weighted sequence demonstrating a small residual cystic mass in the anteromedial left sciatic notch with a size of +-1.03 x 0.78 x 2.60 cm.
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F4
Then, an MRI evaluation was also carried out after surgery; only a small residual cystic mass was obtained (Fig. 4).