Diffuse glioma is a term used to encompass a variety of poorly marginated infiltrating central nervous system tumor, which histologically appear similar to Glial cells, specifically astrocytes and oligodendrocytes. These range in biological behavior from very indolent to extremely aggressive and this is reflected in grading that ranges from grade 1 to grade 4.
The term diffuse glioma does not include circumscribed astrocytic tumors (e.g. pilocytic astrocytoma, subependymal giant cell astrocytoma, pleomorphic xanthoastrocytoma etc…) nor tumors with admixed neuronal elements (e.g. ganglioglioma) although there is overlap particularly with the latter.
Reports have demonstrated that chromosomal instability, driven in part by gene mutations maintaining overall genomic stability, is found in subsets of adult-type diffusely infiltrating diffuse gliomas of all histologic and molecular grades, with resulting in elevated overall copy number burden, chromothripsis, and poor clinical Glioma prognosis. Still, relatively few studies have examined the effect of this process, due in part to the difficulty of routinely measuring CIN clinically.
Richardson et al. reviewed the underlying mechanisms of CIN, the relationship between chromosomal instability and malignancy, the prognostic significance and treatment potential in various cancers, systemic disease, and more specifically, infiltrating diffuse glioma subtypes. While still in the early stages of discovery compared to other solid tumor types in which CIN is a known driver of malignancy, the presence of CIN as an early factor in gliomas may in part explain the ability of these tumors to develop resistance to standard therapy, while also providing a potential molecular target for future therapies 1).
see also
Under the World Health Organization Classification of Tumors of the Central Nervous System 2021 they are broadly divided into adult and pediatric type tumors.
Increasingly the classification relies on molecular markers rather than histology.
Oligodendroglioma IDH-mutant and 1p/19q-codeleted
Pediatric-type diffuse low-grade gliomas
Diffuse astrocytoma MYB or MYBL1-altered
Polymorphous low-grade neuroepithelial tumor of the young
Diffuse low-grade glioma, MAPK pathway-altered
Pediatric-type diffuse high-grade gliomas
Diffuse midline glioma, H3 K27-altered
Diffuse hemispheric glioma, H3 G34-mutant
Diffuse pediatric-type high-grade glioma, H3-wildtype and IDH-wildtype