case_images: PMC9805627_01
case_images: Axial (a) and sagittal (b) views of enhanced T1-weighted magnetic resonance imaging demonstrating a homogenous enhanced lesion in the dorsal midbrain and a skipped lesion in the right thalamus. The lesion exhibits low intensity on the diffusion-weighted image (c). In the fluid-attenuated inversion recovery image, the lesion is isointense and is accompanied by perifocal edema (d). Positron emission tomography reveals 18F-FDG uptake in the lesion (e).
case_images: SNI-13-574-g001.jpg
case_images: PMC9805627_01_SNI-13-574-g001.jpg
case_images: F1
case_images: In the midbrain lesion, 18F-fluorodeoxyglucose (18FDG) accumulation was also observed on 18F-FDG-positron emission tomography [Figures 1a-e].
case_images: Microscopic intraoperative view of the tumor. The surface of the right upper colliculi is partially swollen and pinkish, and recognizable as a lesion (area surrounded by four arrows). The fourth segment of the posterior cerebral artery (P4) and the basal vein of the Rosenthal are also seen.
case_images: SNI-13-574-g002.jpg
case_images: PMC9805627_01_SNI-13-574-g002.jpg
case_images: F2
case_images: The superior colliculus was mildly enlarged, and the surface was discolored, appearing pale pink [Figure 2].
case_images: Histopathological findings showed large undifferentiated tumor cells with prominent nucleoli (b, arrow) and small lymphocytes by hematoxylin and eosin staining, presenting a so-called "two-cell pattern" (a and b). Immunohistochemical staining showed that the cell membrane and cytoplasm were positive for C-kit staining (c), and the cell membrane was positive for placental alkaline phosphatase immunostaining (d).
case_images: SNI-13-574-g003.jpg
case_images: PMC9805627_01_SNI-13-574-g003.jpg
case_images: F3
case_images: Pathological examination revealed undifferentiated cells with a large round nucleus and prominent nucleoli associated with small lymphocytic infiltration, suggesting a germ cell tumor [Figures 3a and b]. Immunohistochemically, the atypical cells were positive for C-kit and placental alkaline phosphatase [Figures 3c and d].
case_images: Dose distribution of whole-ventricle irradiation (a). Axial (b) and sagittal (c) views of enhanced T1-weighted following completion of chemoradiation therapy. The enhanced lesion disappears. The FLAIR image after 5 years of treatment reveals no recurrence or late radiation morbidity (d).
case_images: SNI-13-574-g004.jpg
case_images: PMC9805627_01_SNI-13-574-g004.jpg
case_images: F4
case_images: Immediately after completing the entire course, MRI confirmed the disappearance of the contrast-enhancing lesions [Figures 4b and c]. No late radiation morbidity such as leukoencephalopathy was observed [Figure 4d].