Intracranial germinoma in the lateral ventricle with polydipsia and polyuria: a case report and literature review.

Central nervous system germ cell tumors (CNSGCTs) are rare neoplasms which usually develop in the midline structures. They are occasionally involved in off-midline structures of the brain. Here, we report an extremely rare case of an intracranial germinoma in the lateral ventricle. The patient was a 10-year-old boy with a 1-year history of polydipsia and polyuria. Brain magnetic resonance imaging (MRI) showed a relatively homogeneously enhancing lesion in the lateral ventricle, and the posterior pituitary gland was not hyperintense on T1-weighted imaging. Subependymoma was suspected, and tumor removal operation was performed; however, because the intraoperative pathological investigation revealed germinoma, we could only perform partial removal of the tumor. Postoperative histology also confirmed germinoma. Then, the patient received chemotherapy, followed by radiation therapy. MRI showed no recurrence for 6 years after treatment. Intracranial germinoma in the lateral ventricle is extremely rare. The diagnosis is occasionally challenging, especially when the tumors are located in atypical locations. This paper presents a literature review of previously described CNSGCTs of the lateral ventricle to improve awareness of CNSGCTs in atypical locations. We also consider the relationship between imaging findings and clinical manifestations.