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Basal ganglia germinoma in an adolescent: A case report

Introduction Germ cell tumors are rare tumors and may pose a diagnostic dilemma. We present an interesting and rare case of bifocal basal ganglia germinoma which got diagnosed two years after the initial onset of symptoms. Case A fifteen years old boy presented with insidious onset right hemiparesis followed by polyuria & polydipsia. Later, he also developed cognitive decline and speech disturbances. Serial MRIs (figure 1) over a 2-year period showed progressive atrophy of the left caudate nucleus, along with Wallerian degeneration of the left internal capsule and crus of midbrain. Further in the course, imaging revealed (figure 2) an ill-defined signal intensity involving left caudate nucleus, internal capsule and thalamus, with increased perfusion & calcification, which was suggestive of basal ganglia germinoma. Posterior pituitary bright spot was absent in T1 sagittal images. Beta HCG levels in both CSF & serum were mildly elevated, AFP levels were normal. Urine osmolality studies & water deprivation test revealed a central diabetes insipidus. As it was bifocal germinoma & CSF markers were typical, biopsy was deferred & chemo-radiotherapy was initiated. On 6 months follow up, mild improvement in symptoms was noted. Conclusion This case illustrates an uncommon presentation of a CNS germinoma, which is often difficult to diagnose early because of its insidious course, atypical symptomatology and MRI findings. Constellation of progressive hemiparesis and diabetes insipidus should have high index of suspicion for basal ganglia germinoma.
Keywords: Hemiparesis, Speech disturbance, polyuria, basal ganglia germinoma