Synonym
Glioblastoma multiforme
Introduction
Glioblastoma is the most common malignant brain tumor in adults. Due to its very poor prognosis, it is classified as the most severe grade according to the WHO classification of primary tumors of the central nervous system, i.e. a grade IV glioblastoma. Glioblastoma belongs to the group of astrocytic tumors (gliomas), which are histologically similar to the cells of the supporting tissue (glial cells) of the brain. Gliomas develop from the precursor cells of the glial cells and are therefore brain tumors (primary brain tumors).
Frequency
Glioblastoma is the most common malignant brain tumor in adults. The incidence of brain tumors in general is said to be around 50 per 100,000 inhabitants and year. Among the primary brain tumors, gliomas are the most common with 4-5 new cases per 100,000 inhabitants and year.
The most frequent glioma is the glioblastoma with over 50% and accounts for about 25% of all primary brain tumors. Thus, the number of new cases of glioblastoma is about 3 per 100,000 inhabitants and year. It most frequently occurs between the ages of 60 and 70.
However, significantly younger people are also affected. Men fall ill almost twice as often as women. Glioblastomas in children are very rare. Compared to other tumors, however, brain tumors are fortunately rare. Only about 2% of all cancer patients suffer from a brain tumor.
Occurrence
Glioblastomas grow everywhere in the central nervous system (CNS), but especially in the cerebrum. They originate from the part of the brain that consists of nerve fibers (white matter). The tumors grow infiltrating, mostly under the cerebral cortex (subcortical), but can also take hold of the cortex.
They can be found in all the lobes of the brain, but also in the so-called beam that connects the two halves of the brain (hemispheres). A glioblastoma that spreads from the beam (corpus callosum) on both sides into the frontal areas of the brain (frontal lobe) is called a butterfly glioma. If the brain tissue is infiltrated over a large area, affecting at least two lobes of the brain, this is called gliomatosis cerebri.
Sometimes glioblastomas also grow along the vault (fornix), which lies under the beam, in the thalamus and rarely also in the middle brain stem. Microscopically, the glioblastoma is characterized by multiform cells of different size and shape with peculiar nuclei. Many of the cells are in the process of nuclear division (mitosis).
The rapid growth of the tumor and the release of a vascular factor produced by the tumor tissue leads to the formation of abnormal (pathological) vessels with a defective wall structure. This leads to small vascular dilatations (aneurysms and varices), short circuits of arteries and veins (arteriovenous anastomoses) and so-called “early veins”. This often leads to bleeding (apoplectic glioma) and inadequate nutrition of the tumor, resulting in the death of active cells (necrosis) within the tumor. These necrotic tumor areas are often surrounded by pseudopallisades, which consist of linearly arranged neoplastic cells. In addition, swelling of the tissue develops due to an accumulation of fluid from the vascular system around the tumor (peritumoral edema), which often leads to swelling of the entire hemisphere of the brain.
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