Glial Tumors: Diffuse Gliomas

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the most common subtype of primary glioblastoma in older adults?

IDH-mutant

FGFR1-mutant

BRAF V600-mutant

IDH-wildtype (correct)

What is a characteristic genetic feature of pediatric low-grade gliomas?

EGFR gene amplifications

FGFR1 or MYB alterations (correct)

H3 K27M mutations

TERT mutations

What is the most common genetic alteration in WHO grade II-III diffuse astrocytomas and oligodendrogliomas?

Spontaneous mutations of the IDH gene complex (correct)

H3 G34R/V mutations

BRAF V600 mutations

EGFR gene amplifications

What is the term for the process by which diffuse astrocytomas tend to progress biologically?

Stepwise accumulation of defined genetic abnormalities Signup and view all the answers

What is the name of the cell type that resembles non-neoplastic 'fibrous' astrocytes?

Fibrillary cells Signup and view all the answers

What is a characteristic cytogenetic alteration of IDH-wildtype glioblastomas?

Trisomy 7 and monosomy 10 Signup and view all the answers

What is a subtype of glioblastoma that is characterized by BRAF V600 mutations?

Epithelioid glioblastomas Signup and view all the answers

What is the term for the earliest genetic alterations in WHO grade II-III diffuse astrocytomas?

Initiating events Signup and view all the answers

What is the characteristic growth pattern of diffuse gliomas?

Infiltrative growth along white matter tracts and perivascular spaces Signup and view all the answers

What is the purpose of the revised WHO 2016 classification scheme?

To combine key morphologic and genetic features for biologically uniform diagnoses Signup and view all the answers

What percentage of glioblastoma patients were found to have IDH mutations?

10% Signup and view all the answers

What is the approximate percentage of lower-grade gliomas with IDH mutations?

80% Signup and view all the answers

What is the role of ATRX and TP53 mutations in glioma development?

They drive the precursor cell towards the astrocytoma morphology Signup and view all the answers

What is the term used to describe the areas where individual tumor cells spread, including white matter tracts, perivascular spaces, subpial regions, and surrounding neurons?

Secondary structures of Scherer Signup and view all the answers

What is the result of 1p19q codeletion with mutations of TERT, CIC, and FUBP1 in glioma development?

They drive the precursor cell towards the oligodendroglioma morphology Signup and view all the answers

What is the significance of the finding that IDH-mutant diffuse astrocytomas and oligodendrogliomas have more in common with each other?

It suggests that they share a common molecular mechanism Signup and view all the answers

Study Notes

Glial Tumors

Diffuse gliomas are a group of glial neoplasms that grow in an infiltrative manner, spreading along white matter tracts, perivascular spaces, subpial regions, and surrounding neurons.
Diffuse gliomas are classified into different categories based on morphologic and genetic features, leading to more biologically uniform diagnoses.

IDH-Mutant and IDH-Wildtype Gliomas

IDH-mutant diffuse astrocytomas and oligodendrogliomas have more in common with each other than with other entities previously categorized based on lineage assumptions.
Mutations in the IDH gene are found in 10% of glioblastoma patients and 80% of lower-grade (WHO grade II-III) gliomas, regardless of astrocytic or oligodendroglial lineage.
Additional mutations such as ATRX and TP53 drive the precursor cell towards astrocytoma morphology, while 1p19q codeletion with mutations of TERT, CIC, and FUBP1 provoke oligodendroglioma phenotype.

Primary Glioblastoma

Primary (de novo) glioblastoma in older adults is IDH-wildtype by definition, often with associated TERT mutations, cytogenetic alterations, and epidermal growth factor receptor (EGFR) gene amplifications.
These tumors vary in epidemiologic features, morphologic attributes, growth patterns, genetic profiles, and clinical behavior.

Pediatric and Anatomic Variants

Pediatric low-grade gliomas often have FGFR1 or MYB alterations.
H3 K27M-mutant diffuse midline gliomas, BRAF V600-mutant epithelioid glioblastomas, and H3 G34R/V-mutant high-grade hemispheric gliomas are examples of genetically distinct subtypes within different anatomic locations.

Diffusely Infiltrating Astrocytomas

Diffusely infiltrating astrocytomas are the largest group, with a tendency to biologic progression that reflects a stepwise accumulation of defined genetic abnormalities.
IDH1 mutations represent the earliest and most common genetic alterations in WHO grade II-III diffuse astrocytomas and secondary glioblastomas.
The fibrillary type is the most frequently encountered and is considered the de facto subtype when discussing diffuse astrocytomas in general.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Learn about the clinical, pathological, and genetic diversity of diffuse gliomas, a type of glial neoplasm that grows in an infiltrative manner.