case_images: PMC11374598_01
case_images: Preoperative MRI. (A) T2-weighted sagittal plane. A heterogenous hyperintense space-occupying the lesion is confirmed within the fourth ventricle. (B) T1-weighted post-contrast sagittal plane. A strong enhanced mass-like lesion is confirmed within the fourth ventricle. An enlarged third ventricle (asterisk) is revealed. (C) T1-weighted transverse plane. Hypo- to isointense lesion is confirmed. (D) T2 fluid-attenuated inversion recovery transverse plane. The lesion is revealed as a hyperintensive signal.
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case_images: PMC11374598_01_fvets-11-1450332-g001.jpg
case_images: fig1
case_images: T1W images, heterogeneous hyperintensity on T2W images, hyperintensity on fluid-attenuated inversion recovery sequences (FLAIR), and marked non-uniform contrast enhancement (Figures 1A-D). The mass compressed and displaced the medulla oblongata ventrally and the cerebellum dorsally.
case_images: Intraoperative images from neurosurgical microscope. (A) A dural incision is made longitudinally from the level of the cerebellar uvula to the level of the atlas. The vermis and dura mater are indicated as a yellow asterisk and a white arrow, respectively. A branch of the caudal cerebral artery is highlighted with a black arrow. (B) An avascular tela choroidea (blue arrow) is incised with a nerve hook probe. The tumor (white asterisk) is confirmed through the incision. (C) Two green-stringed neurosurgical sponges are packed around the tumor to retract the brain parenchyma and secure the surgical field. (D) Through repeated meticulous maneuvers using tumor forceps, a hook probe, and a micro-ring curette, the tumor is bluntly dissected from the fourth ventricle (E) The tumor is removed, and the space (double white asterisks) of the fourth ventricle is confirmed. (F) The remaining suspected tumor capsule (green asterisk) is partially resected. The remaining choroid plexus is highlighted with a green arrow.
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case_images: PMC11374598_01_fvets-11-1450332-g002.jpg
case_images: fig2
case_images: When the caudal fossa was sufficiently exposed, a neurosurgical microscope was used to magnify the surgical site and capture the image (Figure 2).
case_images: Postoperative MRI. (A,B) Immediate postoperative T1-weighted post-contrast MRI. A contrast-enhanced lesion (yellow arrow) is revealed on the caudoventral aspect of the cerebellum. The third ventricle (yellow asterisk) is still enlarged. (C,D) 8-month postoperative T1-weighted post-contrast MRI. Contrast-enhanced lesion (white arrow) and the third ventricle (white asterisk) are reduced compared to the former MRI findings.
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case_images: PMC11374598_01_fvets-11-1450332-g003.jpg
case_images: fig3
case_images: T1W with gadolinium images (Figures 3A,B). The tumor was white to gray, oval-shaped, 15.8 x 10.5 x 10 mm, and firm (Figure 4A). The former contrast-enhanced structure had reduced significantly and appeared to be a membranous structure (Figures 3C,D).
case_images: Tumor gross appearance and biopsy results. (A) A resected fourth ventricular tumor. The gross appearance is white to gray (relatively low vascularization), oval-shaped, 15.8 x 10.5 x 10 mm in size, and has a firm texture. (B) Dense spindle cells with an abundant collagen matrix are confirmed. These findings are typical findings of the fibrous subtype of meningioma (magnification x20, black 50 mum scale bar, hematoxylin and eosin stain). (C) Oval-shaped nucleated cells with small whorls (black arrow) are revealed, indicating the meningothelial subtype meningioma. (magnification x40, black 50 mum scale bar, hematoxylin and eosin stain).
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case_images: PMC11374598_01_fvets-11-1450332-g004.jpg
case_images: fig4
case_images: T1W with gadolinium images (Figures 3A,B). The tumor was white to gray, oval-shaped, 15.8 x 10.5 x 10 mm, and firm (Figure 4A). Histological examination revealed dense spindle cells with an abundant collagen matrix, the typical finding of the fibrous subtype, and oval-shaped nucleated cells with small whorls, the common finding of the meningothelial subtype (Figures 4B,C).