MR imaging findings of germ cell tumors arising from the basal ganglia: focused on early imaging finding

Abstract

Germ cell tumor (GCT) arising in the basal ganglia or thalami is relatively uncommon. It occurs most commonly in boys during second decade of life. It is difficult to diagnose early stage GCTs in these regions because the images are not so typical and the symptom onset is insidious. However, early diagnosis of this tumor is important because of the high radiosensitivity and potential curability. Early stage GCTs originating from the basal ganglia or thalami appear as ill-defined small patchy lesions. They frequently present as hyperintense lesions compared with deep gray matter on T2-weighted image without cyst, mass effect, or prominent enhancement. Microhemorrhages can be accompanied infrequently. These tumors are mostly associated with ipsilateral hemiatrophy at the time of presentation. During tumor progression, tiny cysts develop at a relatively early stage, and intratumoral cyst, hemorrhage, and ipsilateral hemiatrophy gradually tend to be more pronounced. Ultimately, these become overt large mass with remarkable heterogenous enhancement, containing multiple cysts of various sizes and hemorrhage. This review aims to describe the serial MR imaging findings of the GCTs arising from basal ganglia or thalami, focusing on the early finding.