Coronal sections through several levels of brain show a large necrotic, variegated tumor on the left in the temporal lobe and adjacent regions characteristic of a glioblastoma multiforme. Note the shift of structures from left to right with a decrease in size of the lateral and third ventricles which is due to mass effect which often causes hernation which produces death. The exact etiology is not known but has to do with several mutations in protooncogenes and tumor suppressor genes. Some appear as a part of several hereditary syndromes such as neurofibromatosis or Turcot's syndrome. The cause of the glioblastoma or any brain tumor is not known but changes or loss of chromosome 17 and inactivation of a tumor suppressor gene, p53, play a role.
Glioblastomas are the most comman primary brain tumor.
Younger patients tend to have a better prognosis than the elderly. Radiation and chemotherapy appear to extend the life of the patient. Usually the glioblastoma is seen as a mass lesion involving a focal area although it may cross the corpus callosum to the other hemisphere or be multifocal. Microscopically the glioblastoma has many forms as well. Is a highly cellular tumor with pleomorphic, basophilic nuclei with indistinct cytoplasmic borders or plump pink cytoplasm and a delicate fibrillary background.