A Unique Magnetic Resonance Imaging Feature of Glioblastoma Multiforme: The ‘Pseudopalisade’ Sign

This study was designed to investigate the unique magnetic resonance imaging (MRI) appearance of histopathologically-proven glioblastoma multiforme (GBM) with pseudopalisade necrosis and to assess its value for grading gliomas and providing a differential diagnosis. The study included 169 patients with intracranial masses who underwent surgery and had a proven histopathological diagnosis: 50 with GBM, 77 with gliomas (46 grade II and 31 grade III) and 42 with other intracranial masses (20 metastases, 14 lymphomas and eight abscesses). All patients underwent pre-operative brain MRI including post-contrast T1-weighted imaging. The presence of the ‘pseudopalisade’ sign on post-contrast T1-weighted images was compared among the different types of brain mass. The frequency of the ‘pseudopalisade’ sign in GBMs (94.00%) was significantly higher than that seen in grade II and III gliomas (11.69%) and other intracranial masses (7.14%). The ‘pseudopalisade’ sign on post-contrast T1-weighted images was useful for grading gliomas and for differentiating GBM from other brain masses.