Third Ventricular Glioblastoma Multiforme: Case Report & Literature Review
Glioblastoma multiforme (GBM) typically presents in the cerebrum, localized to the frontal, temporal, or parietal lobes. The usual radiographic finding is a ring-enhanced lesion, with areas of necrosis on Magnetic Resonance Imaging (MRI). Here, we present a case of a sixty-two year old female with headaches, increasing somnolence and cognitive decline over several weeks. MRI showed mild hydrocephalus with a well marginated, homogenous, and non-hemorrhagic lesion of the posterior third ventricle. The lesion was found extending between the leaves of the septum pellucidum, and the body of the fornix, without evidence of either necrosis or ring enhancement on post-contrast T1-weighted MRI imaging (Fig. 1a). Final pathology reports confirmed the diagnosis of GBM, including GFAP by immunohistochemistry and a high Ki-67 by immunohistochemistry. There were also classic microscopic findings such as a serpentine patter of necrosis, surrounding hypercellularity, and the characteristic perinecrotic pseudo-palisading pattern of GBM (Fig. 2). This case report describes an unusual location for the most common primary brain neoplasm. Moreover, this case also identifies the origin of a GBM related to the paracentral ventricular structures, interpositioning itself between the body of the fornix and leaves of the septum pellucidum. We also review the existing literature on rare incidents of glioblastomas that were reported to be isolated to the third ventricle. A discussion of the current theories on the potential origins of glioblastoma follows, and we also propose a hypothesis for how such lesions can form in the third ventricle. Moreover, the radiographic findings in this case did not show any evidence or typical characteristic attributable to GBM. To our knowledge this is the first reported case of a GBM found in this anatomical location, with such atypical radiographic presentation.