PMC5073084_01
Computed tomography and magnetic resonance imagings. a There was a mild hyperintense 16-mm-diameter mass without calcification at the foramen of Monro causing obstructive hydrocephalus. b, c T1- and T2-weighted images showed the well-delineated mixed-signal heterogeneous core. The typical peripheral hemosiderin rim of low signal intensity was not seen on T2-weighted imaging. d No perilesional edema was presented on the fluid-attenuated inversion recovery magnetic resonance image. e Diffusion-weighted imaging showed an isointense mass; only a portion of the mass was hyperintense. f T2-star-weighted imaging showed a hypointense mass
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Fig1
Monro, and the mass was causing obstructive hydrocephalus. MRI revealed a well-delineated mass at the foramen of Monro with heterogeneous signal intensity on both T1- and T2-weighted images; the mixed-signal core appeared as a popcorn-like lesion typical of cavernous angioma (Fig. 1).
a Axial, b coronal, and c sagittal gadolinium-enhanced T1-weighted imaging demonstrated mild mass enhancement
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Fig2
T1-weighted imaging revealed mild enhancement of the mass (Fig. 2). There were no vascular abnormalities on CT angiography or CT venography.
Intraoperative photographs of the mass resection procedure. a Intraoperative neuroendoscopy image showing the reddish lobular mass with hematoma and obstruction of the foramen of Monro. b Cavum septum pellucidum had already occurred because of the high intracranial pressure associated with hydrocephalus. c Insertion of clear plastic sheath (ViewSite) into the brain. d The mass was bluntly dissected from the ventricle wall by one surgeon. e Total en bloc resection of the mass was performed
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Fig3
We performed endoscope-assisted transcortical removal of the mass (Fig. 3).
Photomicrograph of the lesion showing large vascular spaces filled with an organized thrombus Specimens were stained with hematoxylin and eosin. a x100 magnification. b x400 magnification
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Fig4
Histological examination revealed a cavernous angioma with evidence of large vascular spaces filled with an organized thrombus (Fig. 4). 
Postoperative imaging showed no evidence of residual mass, and demonstrated improvement of hydrocephalus. a Postoperative computed tomography image, b T2-star-weighted image, and c gadolinium-enhanced T1-weighted image
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Fig5
Postoperative MRI confirmed complete removal of the tumor, and a return to normal ventricular size (Fig. 5).