glioblastoma multiforme
Meaning of glioblastoma multiforme: The commonest malignant brain tumor in adults, named for how many different faces it presents under a microscope.
Definition of glioblastoma multiforme
Glioblastoma multiforme is a fast-growing malignant tumor arising from glial cells, the supporting cells of the brain. The word multiforme records its appearance on a slide, where crowded abnormal cells sit beside patches of dead tissue and clusters of misshapen new blood vessels. It spreads by infiltrating along nerve fiber tracts rather than forming a lump with a clean edge.
What does multiforme mean?
It means many forms, and it describes variation within a single tumor. One region may be densely packed with dividing cells while another has outgrown its blood supply and died, leaving a core of dead tissue ringed by cells crowded around it. Fresh vessels sprout in disordered tangles. Two samples taken centimeters apart can look like different diseases, which is one reason a small sample can mislead.
How is it classified now?
The naming has changed. Current classification uses molecular features rather than appearance alone, and the diagnosis of glioblastoma requires the tumor to lack a mutation in the IDH enzyme. Tumors that look the same but carry that mutation are placed with the astrocytoma group and behave differently. The word multiforme has largely been dropped, so a modern report is more likely to read simply glioblastoma. Older records and much of the published literature still carry the longer name.
Why is it so difficult to remove?
| Feature | Consequence |
|---|---|
| Infiltrating edge | Cells extend well beyond what a scan shows |
| Spread along fiber tracts | Reaches the opposite side of the brain |
| Critical surroundings | Wide margins would cost speech or movement |
| Blood-brain barrier | Limits which drugs reach the tumor |
Because the boundary seen on imaging is not the true boundary, this brain tumor almost always regrows near the site of the original, and surgery aims to remove as much as can be taken safely rather than to cure.
What symptoms does it produce?
Symptoms usually build over weeks rather than months. Headache that is worse on waking, new seizures in an adult, weakness on one side, difficulty finding words, and changes in personality or judgment are typical, and which of them appears depends entirely on which part of the brain is involved. Swelling in the surrounding tissue often contributes as much to the symptoms as the tumor itself.
Also known as
Used in a sentence
Imaging showed a ring-enhancing lesion later confirmed as glioblastoma multiforme.
Good to know
The term has largely been replaced by glioblastoma, and current classification requires the absence of an IDH mutation, so an older label does not always map onto a current diagnosis.
Word origin
Where “glioblastoma multiforme” comes from
Glia is Greek for glue, blastos means a germ or sprout, and the Latin multiforme means having many forms.