Imaging description

Intraventricular tumors (IVTs) have diverse demographics and histogenesis. Ependymomas (Fig. 31.1) and choroid plexus tumors (Figs. 31.2, 31.3) are relatively common entities, particularly in the pediatric group, and should be considered first in the differential diagnosis. Although considered to be prototypical IVTs, subependymomas and neurocytomas (Fig. 31.4) are actually much less common than meningiomas (Fig. 31.5) and metastases (Fig. 31.6). Chordoid glioma of the third ventricle and rosette-forming glioneural tumor of the fourth ventricle are unique IVTs, although they are much less common than astrocytomas, oligigodendrogliomas, and glioblastomas (Figs. 31.7, 31.8). Lateral ventricular neoplasms account for 50% of all intraventricular tumors in adults and 25% in children.

Although these neoplasms are easily detected with CT and MRI, both techniques are relatively non-specific in identifying the type of tumor [1]. Per anatomic location, supratentorial intraventricular masses can be classified into ependymal, subependymal, choroid plexus, parenchymal, septum pellucidum, foramen of Monro, third ventricular, or aqueductal in origin. Infratentorial intraventricular masses can be ependymal, subependymal, vermian, cerebellar, or choroid plexus in origin. Correlation of demographic, clinical, and imaging features of IVTs allows creating a comprehensive differential diagnosis [2].

Most ependymomas will occur in the fourth ventricle. When supratentorial in location, intraventricular ependymomas are less common than parenchymal ependymomas. They are associated with calcifications or cyst formation in 50% of the cases and hemorrhage in about 10% [2]. They are associated with high incidence of incomplete tumor resection and permanent neurological complications associated with their removal [3].