PMC7294175_01
Preoperative magnetic resonance images (MRI). Preoperative MRI showed right frontal mass lesion. The lesion was isointense in T1-weighted MRI (a), hyperintense in T2-weighted MRI (b), hyperintense in fluid attenuation inversion recovery image (c), and homogenous enhanced with gadolinium intravenous injection (d: Axial image, e: Coronal image, and f: Sagittal image).
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T1-weighted MRI [Figure 1a], was hyperintense on T2-weighted MRI [Figure 1b], and also hyperintense on fluid attenuation inversion recovery MRI [Figure 1c]. The lesion demonstrated homogenous enhancement on Gd-T1-weighted MRI [Figure 1d-f].
Digital subtraction findings (DSA). Preoperative DSA showed some feeding arteries (right middle cerebral artery branch [Right carotid artery angiography (Rt CAG)], a: Axial view, b: Lateral view), right anterior cerebral artery branch (Lt CAG, c: Axial view, d: Lateral view), and right middle meningeal artery (MMA) branch (Rt external CAG, e: Axial view, f: lateral view). Preoperative feeder embolization targeted to right MMA branch was performed (Rt external CAG, g: Axial view, h: Lateral view).
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Digital subtraction angiography showed some feeding arteries (right middle cerebral artery branch) [Figure 2a and b], right anterior cerebral artery branch [Figure 2c and d], and right middle meningeal artery (MMA) branch [Figure 2e and f]. Preoperative feeder embolization targeted to the right MMA branch was performed [Figure 2g and h].
Intraoperative findings and postoperative MRI findings. During surgery, tumoral invasion beyond the dura mater was observed (a). When the dura was opened, a well-demarcated, firm, spherical tumor was observed beneath the arachnoid membrane. The tumor was elastic, hard, grayish in color, and loosely adherent to but separable from the dura mater (b). The tumor was totally removed piece by piece, with the adjacent brain tissue and dura (c). Postoperative MRI showed the total removal of the tumor (d: Axial view, e: Coronal view, f: sagittal view).
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During surgery, tumoral invasion beyond the dura mater was observed [Figure 3a]. The tumor was elastic, hard, grayish in color, and loosely adherent to but separable from the dura mater [Figure 3b]. The tumor was totally removed piece by piece, with the adjacent brain tissue and dura [Figure 3c]. Postoperative MRI showed the total removal of the tumor [Figure 3d-f].
Histology findings. Compact bundles of thin, elongated, finely fibrillated cells, which tend to exhibit nuclear palisading (Antoni Type A) and which are intermingled with a looser pattern of Antoni Type B, can be observed. The adjacent cortex contained no tumor cells (a: hematoxylin and eosin (HE); original magnification, x10). Immunohistochemical staining was positive for S-100 protein (b) but negative for glial fibrillary acidic protein (GFAP), cluster of differentiation (CD) 34, epithelial membrane antigen (EMA) (c), signal transducer and activator of transcription 6 (STAT 6) (d), progesterone receptor (PgR), and synaptophysin. The histopathological diagnosis was schwannoma. The tumor was observed to be in the subarachnoid space extending to the outer space of dura-mater, intimately attached to the pia mater (e: HE staining, f: Synaptophysin immunostaining).
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In light-microscopic assessments, the tumor was composed predominantly of Antoni Type A, and intermingled with Antoni Type B [Figure 4a]. Immunohistochemical staining was positive for S-100 protein [Figure 4b] but negative for glial fibrillary acidic protein, cluster of differentiation 34, epithelial membrane antigen [Figure 4c], signal transducer and activator of transcription 6 [Figure 4d], progesterone receptor, and synaptophysin. The tumor was observed to be in the subarachnoid space extending to outer space of dura mater, intimately attached to the pia mater [Figure 4e and f].