PMC10101703_01
Preoperative magnetic resonance imaging (MRI). a, b: Axial images of the T2-weighted and T2-FLAIR (fluid-attenuated inversion recovery) showing diffuse hyperintense swelling of the brainstem c: Diffusion-weighted image showing spotty high intensity in the ventral pons. d: T1-weighted gadolinium (Gd)-enhanced MRI showing no apparent contrast enhancement in the tumor. e-g: T2-weighted MRI showing enlarged lateral ventricles due to CSF obstruction with tonsillar herniation in the posterior fossa. h: 11C-methionine was partially concentrated in the sites of the pons on position emission tomography (PET) scan.
2188-4226-10-0075-g001.jpg
PMC10101703_01_2188-4226-10-0075-g001.jpg
g001
MRI showed an intramedullary tumor expanding infiltratively surrounding the pons and lateral ventricles enlarged due to cerebrospinal fluid (CSF) obstruction with tonsillar herniation in the posterior fossa (Fig. 1a-g). T1-gadlinium image, although partial high uptake on a 11C-methionine positron emission tomography (PET) scan was observed (Fig. 1h), which indicated the possibility of an aggressive feature.
Intraoperative findings and postoperative images. a: A midline suboccipital craniotomy was performed in the supine position and the C1 vertebral arch was resected. The square indicates the area Fig. 2b indicates. b: The epidural layer was decompressed through a midline incision as much as possible. The blue dotted line indicates the median line. c: Postoperative MRI image of T2-weighted. The arrow indicates the biopsied area. d, e: Postoperative CT and CT reconstruction showing the minimal extent of craniectomy and laminectomy.
2188-4226-10-0075-g002.jpg
PMC10101703_01_2188-4226-10-0075-g002.jpg
g002
CSF pressure. Chronologically, a CSF reservoir was placed under the galea, and a midline suboccipital craniotomy (3 cm x 3 cm) with a C1 laminectomy of 20 mm length was performed in the prone position (Fig. 2a-e).
Pathological findings. a, b: Hematoxylin and eosin staining shows moderately increased cellularity. c: Immunohistochemical analyses show positive staining for ATRX. d: IDH1 R132H was positive. e: Ki-67-positive rate was low. f: p53-positive rate was approximately 25%.
2188-4226-10-0075-g003.jpg
PMC10101703_01_2188-4226-10-0075-g003.jpg
g003
However, there was no mitotic activity or anaplasia (Fig. 3a-b). The Ki-67-positive rate was low, and the p53-positive rate was approximately 25% (Fig. 3c-f).
MRI follow-up post-surgery. a, b: Postoperative T2-weighted image indicating improvement of hydrocephalus and periventricular edema. c, d: Images indicating that a space and a flow void of the CSF at the foramen magnum were visualized (white arrowhead). e: T1-weighted gadolinium (Gd)-enhanced MRI showing no apparent contrast enhancement in the tumor.
2188-4226-10-0075-g004.jpg
PMC10101703_01_2188-4226-10-0075-g004.jpg
g004
Postoperative MRI visualized the CSF space at the foramen magnum, followed by improvement of the hydrocephalus and periventricular edema (Fig. 4). Postoperative treatment is currently postponed because the tumor size follow-up with MRI demonstrated no marked change for 12 months.