PMC8202391_01
(a-d) Preoperative magnetic resonance images (a) axial unenhanced T2 weighted magnetic resonance imaging showing right-sided lesion (white arrow) and hyperdense areas which extends to the left cerebellum (hemorrhage) and there is no edema round the lesion. (b) Axial postcontrast T1 image, showing bilateral vermian lesions in which the right-sided mass is enhancing gadolinium peripherally. (c) Postcontrast sagittal image, demonstrating partly attachment of the mass to the tentorium. (d) Postcontrast coronal image demonstrates bilateral lesions close to the tentorium in mixt intensity
AJNS-16-200-g001.jpg
PMC8202391_01_AJNS-16-200-g001.jpg
F1
T1-weighted images showed mostly peripheral contrast-enhancing lesion which was partly attached to the tentorium [Figure 1]. The patient underwent a right paramedian suboccipital craniectomy.
(a-d) Intraoperative images. (a) Initial surgical view of the tumor, originating from the tentorium (white arrow) after retraction of cerebellum inferiorly. (b) Bipolar coagulation of the tumor feeders and detachment of the tumor from the tentorium. (c) Surgical view of the tumor (white arrow) after total detachment. (d) Removal of the tumor in a single piece (white arrow) fashion
AJNS-16-200-g002.jpg
PMC8202391_01_AJNS-16-200-g002.jpg
F2
Following the relaxation of the cerebellum and opening the supracerebellar corridor, the lesion was seen 3 cm in depth in a close anatomical relationship with the tentorium, which is not expected in such intraaxial lesion [Figure 2].
(a-c) Postoperative magnetic resonance images demonstrating no residual tumor. (a) Axial enhanced T1 imaging. (b) Sagittal enhanced T1 imaging. (c) Coronal T2 imaging
AJNS-16-200-g003.jpg
PMC8202391_01_AJNS-16-200-g003.jpg
F3
Due to the effective cerebellar relaxation, peritumoral dissection was performed easily, remaining feeders were coagulated, and tumor was totally removed en bloc [Figure 3]. Postoperative MRI showed no residual mass [Figure 3a-c].
(a-c) Histopathological images. (a) Anomalous vascular channels, some of them are associated thrombus and fibrosis. Well circumscribed dilated large blood vessel containing papillary structures in the lesion is marked with an arrow, (H and E, x40) (b) High magnification view of the (arrow) marked area. The delicate papillary structures are covered by a thin endothelial lining. No significant atypia, mitotic activity, or necrosis are seen, (H and E, x100). (c) Strong immunopositivity for CD-31 in most of the endothelial cells lining small vessels and papillary structures CD31 x100
AJNS-16-200-g004.jpg
PMC8202391_01_AJNS-16-200-g004.jpg
F4
An associated thrombus was also seen, but no significant atypia, mitotic activity, or necrosis were present [Figure 4a and b]. Staining for CD34 and CD31 highlighted endothelial cells lining papillary structures and vascular channels [Figure 4c].