Germinomas of the Basal Ganglia and Thalamus: Four Case Reports

BACKGROUND The early diagnosis of basal ganglia and thalamus germinomas is often difficult due to the absence of elevated tumor markers, and atypical clinical symptoms and neuroimaging features. CASE SUMMARY Four male children aged 8 to 15 years were diagnosed with germinomas in the basal ganglia and thalamus by stereotactic biopsy from 2017 to 2019. All patients developed hemiplegia except patient 4 who also had cognitive decline, speech disturbance, nocturnal enuresis, polydipsia, polyuria, precocious puberty and abnormalities of thermoregulation. All four cases were alpha-fetoprotein and beta-human chorionic gonadotrophin (β-HCG) negative except patient 3 who had slightly elevated β-HCG in cerebrospinal fluid (CSF). No malignant cells were detected in the patients’ CSF. Brain magnetic resonance imaging findings were diverse in these patients with the exception of the unique and common characteristics of ipsilateral hemisphere atrophy, especially in the cerebral peduncle. All patients were diagnosed with germinomas of the basal ganglia and thalamus by stereotactic brain biopsy. CONCLUSION Stereotactic brain biopsy is necessary to confirm the diagnosis of ectopic germinomas. Serial neuroimaging studies can not only differentiate disease but also determine the biopsy site.