A previously healthy 46-year-old woman presented to our department with a 6-month history of mild headache. Intracranial computed tomography (CT) revealed an iso-dense mass without calcification in the anterior area of the third ventricle. Magnetic resonance imaging (MRI) demonstrated that the tumor (diameter, 14 × 18 × 18 mm) was predominantly isointense on T1-weighted imaging (T1WI) and T2-weighted imaging (T2WI), and homogeneously enhanced to a high degree with gadolinium (Gd) []. The optic chiasma was displaced downwards, and the anterior wall of the third ventricle was deviated. Perilesional edema reaching up to the mesencephalon bilaterally and the internal capsule associated with compression by the tumor mass were clearly observable on fluid-attenuated inversion recovery (FLAIR) MRI []. No pituitary insufficiency was evident from laboratory examinations. Preoperative differential diagnoses included intraventricular meningioma, craniopharyngioma, ependymoma, and chordoid glioma of the third ventricle. To confirm the histological diagnosis, the tumor was resected microsurgically under an interhemispheric translamina terminalis approach to the third ventricle. Intraoperative examination demonstrated that the tumor was firm, rubbery, and nonsuckable, and appeared to be originating from the lamina terminalis with a clear margin between normal structures including the hypothalamus. We achieved gross total resection of the tumor to reduce compression of the optic nerve. Histopathological examination with hematoxylin and eosin (HE) staining of the tumor showed a neoplastic tissue comprising eosinophilic epithelioid cells with large nucleoli arranged in small sheets, within mucinous stroma. Sparse lymphocytic infiltrate was present, and no mitosis was detected []. Immunohistochemical studies were performed using antibodies for glial fibrillary acidic protein (GFAP) (rabbit polyclonal antibody; DAKO; ready to use), CD34 (mouse monoclonal antibody; clone 9BEnd10; DAKO; ready to use), thyroid transcription factor (TTF)-1 (mouse monoclonal antibody; clone 8G7G3/1; DAKO; ready to use), and Ki-67 (mouse monoclonal antibody; clone MIB-1; DAKO; ready to use). Most tumor cells showed immunoreactivity for GFAP and CD34. In addition, almost all tumor cells appeared strongly positive for TTF-1 []. The Ki-67 (MIB-1) proliferation-related labeling index was low, at 2.0% []. With regard to the genetic profile, these tumor cells were immunonegative for R132H-mutated isocitrate dehydrogenase-1. Taking all these results into account, the final diagnosis was chordoid glioma of the third ventricle in accordance with the 2016 WHO Classification of Tumors of the central nervous system (CNS).[] The postoperative course was uneventful and her headache improved immediately. MRI at 1 year after the initial treatment did not show any residual tumor [].