Abstract
Adult pilocytic astrocytoma often presents with more aggressive behavior and poorer clinical outcomes than generally appreciated as pilocytic astrocytoma. Additionally, mortality increases with age at diagnosis; even more so for intraventricular lesions. Adult intraventricular pilocytic astrocytoma is extremely rare, and the clinical characteristics and pathological information are not well-described. We report a 75-year-old woman who presented with a progressive gait disorder, cognitive function decline, and impaired consciousness. Magnetic resonance imaging revealed hydrocephalus and an intraventricular tumor extending along the medial wall of the lateral ventricle, with another isolated lesion. Endoscopic surgical resection was performed to remove the tumor at the septum pellucidum safely, and the histologic and molecular findings were consistent with pilocytic astrocytoma. This case involved unique characteristics as the oldest known patient with intraventricular pilocytic astrocytoma at the rare location of the septum pellucidum and with multiple lesions. This case may aid the diagnosis in similar cases. It is important to consider this diagnosis in the differentials for intraventricular neoplasms. Further studies to elucidate specific molecular findings and indications for appropriate treatment are required to improve patient outcomes.