CASE A
A 54-year-old asymptomatic woman. FLAIR, fluid attenuated inversion recovery.

CASE B
A 53-year-old woman presenting with dizziness, diplopia, and blurred vision.

CASE C
A 32-year-old Latin American woman presenting with a severe headache. CT, computed tomography; DWI, diffusion-weighted imaging; FLAIR, fluid attenuated inversion recovery.

CASE D
A 37-year-old man presenting with a 1-year history of headaches, fatigue, and memory loss. CT, computed tomography.

CASE E
A 17-year-old boy presenting with a history of chronic headaches.

DESCRIPTION OF FINDINGS

  • Case A: A small, T1 and T2 hyperintense, nonenhancing, anterior, third ventricular mass.

  • Case B: A homogeneously enhancing, T2 isointense mass in the anterior floor of the third ventricle containing small cystic areas.

  • Case C: A small cystic lesion with a focus of mural calcification in the posteroinferior third ventricle obstructing the cerebral aqueduct and causing hydrocephalus.

  • Case D: A large heterogeneously enhancing third ventricular mass containing punctate calcifications and scattered small areas of intrinsic T1 hyperintensity.

  • Case E: A predominantly T2 isointense, homogeneously enhancing posterior third ventricular mass.

Diagnosis

Case A

Colloid cyst (presumptive; 14-year imaging stability)

Case B

Chordoid glioma (proven by pathology)

Case C

Intraventricular neurocysticercosis (IVNCC) (presumptive; positive serology in an immigrant from Latin America)

Case D

Craniopharyngioma (proven by pathology)

Case E

Germinoma (proven by pathology)

Summary

True third ventricular masses are rare, with the colloid cyst representing the only primary lesion of the third ventricle that can be termed “common.” The recently described chordoid glioma represents a rare primary tumor that arises exclusively in the third ventricle.

In addition to colloid cysts and chordoid gliomas, other rare differential considerations that may occur as primary to the third ventricle (but more commonly elsewhere) include choroid plexus papilloma (CPP) and choroid plexus carcinoma (CPC), neurocysticercosis (NCC), and ependymoma. Metastases are a differential consideration in the setting of a central nervous system neoplasm with a propensity for CSF spread or in persons with advanced systemic malignancies. Furthermore, masses that arise from the suprasellar and pineal regions often appear to be arising from the third ventricle.

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