Germinoma of basal ganglia

Abstract

Basal ganglia germinomas (BGGs) are rare lesions. Because of the atypical features of early-stage clinical symptoms and imaging characteristics, BGGs are easily misdiagnosed with non-tumorous conditions. This article presented cases of 2 young male patients who came to the hospital due to right arm weakness. Brain Magnetic Resonance Imaging (MRI) images in the first case revealed a lobulated mixed component mass on the left basal ganglia. The solid part showed restricted diffusion on diffusion-weighted imaging, heterogeneous strong enhancement, and no signal of calcification or bleeding. The second case in the left putamen showed hypointensity on T2*, mild enhancement, and atrophy of the ipsilateral cerebral peduncle, increased choline, and decreased n-acetyl-aspartate (NAA) on spectroscopy. Follow-up MRI after 6 months showed a mass increase in size and hypointensity part on T2*. BGGs have been confirmed on biopsy in both cases. With isolated chemotherapy application, there is no sign of remission in the first patient. The second patient was treated with chemotherapy and radiotherapy, and MRI images after treatment showed a complete response.

Keywords: Basal ganglia; Germinoma; MRI.

Fig. 1

Case 1: MRI images (A) axial Fluid-attenuated inversion recovery (FLAIR), (B) coronal T2 Weighted (T2W), (C) Diffusion-weighted imaging(DWI), (D) axial T2*, (E) sagittal T1 Weighted (T1W), (F) post-contrast axial T1W illustrated a mixed signal mass in the left basal ganglia and internal capsule. (A) Axial FLAIR image showed a mixed signal mass comprising a cystic portion (small arrow) and a solid portion (arrowhead), which compressed the third ventricle and caused dilation of the upper ventricular system (large arrow). (B) Coronal T2-weighted image displayed a mixed signal mass, including a cystic portion (small arrow) and a solid portion (arrowhead). (C) DWI revealed restricted diffusion on the solid components (arrowhead). (D) Axial T2* showed no calcification or hemorrhage. (arrow: tumor) (E) Sagittal pre-contrast T1-weighted image demonstrated a mixed signal mass with a cystic portion (small arrow) and a solid portion (arrowhead). (F) Axial T1-weighted post-contrast image showed heterogeneous contrast enhancement in the mass (arrow).

Fig. 2

Case 1: Histopathological Images. (A-B) Hematoxylin-eosin staining: Tumor cells with large, round nuclei, prominent nucleoli, multiple mitotic figures, and variable eosinophilic cytoplasm (arrows). The cells are dispersed or form clusters, intermixed with a background rich lymphocytes (arrowhead). (C-E) Immunohistochemistry. (C) SALL4 Marker (+): Nuclei of germ cells stain orange (arrow). (D) CD117 Marker (+): Cell membranes stain orange (arrow). (E) PLAP Marker (+): Cell membranes stain orange (arrow). (A: x100 magnification. B-E: x400 magnification).

Fig. 3

Case 1: Postoperative computed tomography (CT) image after 2 weeks demonstrated a heterogeneous mass in the basal ganglia and thalamic region, extending into the left lateral ventricle (small arrow), a cavity in the brain tissue (arrowhead), and subdural fluid collection (large arrow).

Fig. 4

Case 2: MRI Images, including (A) axial T2W, (B) axial FLAIR, (C) axial T2*, (D) axial DWI, (E) postcontrast axial T1W, demonstrated. (A-B) Axial T2W and FLAIR showed A heterogeneous mass in the left lentiform nucleus comprising a solid portion (arrowhead) and a cystic portion (arrow). (C) Axial T2* showed a calcifying component (arrow). (D) DWI showed a restricted diffusion (arrowhead). (E) Axial T1W post-contrast showed heterogeneous enhancement (arrow). (F) Axial T2W image showed atrophy of the ipsilateral cerebral peduncle (black arrow).

Fig. 5

Case 2: MRI Images, including (A) axial T2W, (B) axial FLAIR, (C) axial SWI, (D) axial DWI, (E) axial ADC, (F) axial T1W post-contrast, (G) spectroscopy, demonstrating. (A-C): A mixed-density mass involving the lentiform nucleus, head of the caudate nucleus, and left temporal uncus, comprising a solid portion (arrowhead) and a cystic portion (small arrow), with calcification (large arrow). (D-E): Restricted diffusion of the solid portion on DWI/ADC (arrowhead). (F) Axial T1W post-contrast: Enhancement of the mass (small arrow). (G): Atrophy of the ipsilateral cerebral peduncle (black arrow).

Fig. 6

Case 2: CT Images showed a mass involving the lentiform nucleus, head of the caudate nucleus, and left temporal lobe uncus, comprising an increased density solid portion (arrowhead) and a cystic portion (white arrow).

Fig. 7

Case 2: Pathological images. (A) Hematoxylin-eosin staining reveals large-sized tumor cells with abundant, clear, round nuclei, relatively uniform cytoplasm, and distinct nucleoli (black arrowhead). (B-C) Immunohistochemistry: (B) OCT3/4 Marker (+): Strong and diffuse positivity. (C) CD117 Marker (+): Strong and diffuse positivity. (A-E: x400 magnification).

Fig. 8

Case 2: Post-treatment MRI image, including (A) axial T2W, (B) coronal FLAIR, (C) axial SWI, (D) axial DWI, (E) axial ADC, (F) axial T1W post-contrast, demonstrated a cystic lesion in the lentiform nucleus, head of the caudate nucleus, and the left temporal lobe uncus, with evidence of bleeding, and no postcontrast enhancement (white arrowhead).