Neurologic Manifestations of Glioblastoma Multiforme Workup

Updated: Nov 09, 2015
  • Author: ABM Salah Uddin, MD; Chief Editor: Stephen A Berman, MD, PhD, MBA  more...
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Laboratory Studies

Routine laboratory workup results often are negative, but excluding a metabolic or infective process is important in an otherwise healthy patient who presents with new-onset seizures or mental status changes for the first time.


Imaging Studies

The preferred workup is diagnostic neuroimaging studies; MRI with and without contrast is the most sensitive and specific study. These tumors characteristically have low-signal intensity on T1-weighted images and high-signal intensity on T2-weighted images. With contrast, the tumors usually enhance. The enhanced T1-weighted images typically have a central hypodensity surrounded by a thick enhancing rim of tumor. See the images below.

T1-weighted axial gadolinium-enhanced MRI demonstr T1-weighted axial gadolinium-enhanced MRI demonstrates an enhancing tumor of the right frontal lobe. Image courtesy of George Jallo, MD.
T2-weighted image demonstrates notable edema and m T2-weighted image demonstrates notable edema and midline shift. This finding is consistent with a high grade or malignant tumor. Image courtesy of George Jallo, MD.

CT scan can be ordered with or without contrast when MRI is contraindicated or unavailable. Consider the following:

  • On CT scan, GBMs have a variable, inhomogeneous hypodense or isodense appearance with surrounding edema.
  • GBMs tend to infiltrate along the white matter tracts and frequently involve and cross the corpus callosum.
  • Approximately 4-10% of GBMs and 30-50% of AAs do not enhance, while a significant percentage of low-grade gliomas do not enhance.

Other Tests

Functional neuroimaging such as positron emission tomography (PET scan), single-photon emission computed tomography (SPECT), or MR spectroscopy may help differentiate the tumor from other benign mass lesions, brain abscess, or toxoplasmosis. However, the definitive diagnosis is confirmed by stereotactic or open brain biopsy. See the image below.

Magnetic resonance spectroscopy is representative Magnetic resonance spectroscopy is representative of a glioblastoma multiforme.

Consider the following:

  • Functional imaging is commonly used to differentiate between treatment-related radiation necrosis and tumor recurrence.
  • Functional imaging is also used in defining the margins of the tumor for surgical resection and planning for the radiation fields.
  • Additionally, functional imaging may be helpful in determining the most abnormal region of the tumor to improve the diagnostic accuracy in case a small biopsy sample is taken.

Histologic Findings

High-grade astrocytomas (HGAs) are extremely heterogenous tumors characterized by varying degrees of increased cellularity, pleomorphism, mitoses, endothelial proliferation, and necrosis. See the image below.

Histopathologic slide demonstrating a glioblastoma Histopathologic slide demonstrating a glioblastoma multiforme.


Many different grading systems exist for gliomas. The current WHO classification of gliomas is based on the presence or absence of 4 histologic criteria: (1) nuclear atypia, (2) mitoses, (3) endothelial proliferation, and (4) necrosis. Grade I tumors have none of the criteria, grade II have at least 1, grade III have at least 2, and grade IV (GBM) have at least 3 or 4 criteria present. Prominent microvascular proliferation and/or necrosis must be one of the criteria for GBM.