Imaging Characteristics of Pediatric Diffuse Midline Gliomas with Histone H3 K27M Mutation

Area of Science:

• Neuro-oncology
• Pediatric Radiology
• Molecular Pathology

Background:

• The 2016 WHO Classification of Tumors of the CNS established "diffuse midline glioma with histone H3 K27M mutation" as a distinct entity.
• Histone H3 K27M mutations are increasingly recognized as a key molecular driver in pediatric midline gliomas.

Purpose of the Study:

• To characterize the MR imaging features of pediatric diffuse midline gliomas with histone H3 K27M mutation.
• To compare imaging findings between histone H3 K27M-mutated and wildtype diffuse midline gliomas.

Main Methods:

• Retrospective review of MR imaging in pediatric patients with midline gliomas.
• Evaluation of imaging features including tumor location, enhancement patterns, and necrosis.
• Correlation of imaging findings with the presence or absence of histone H3 K27M mutation.

Main Results:

• Histone H3 K27M mutation was present in 72.7% of 33 diffuse midline gliomas.
• Tumors were located in the thalamus (27.3%), pons (42.4%), vermis/fourth ventricle (15%), and spinal cord (6%).
• Radiographic features were highly variable, with no significant correlation found between mutation status and enhancement, border characteristics, infiltrative appearance, or edema.

Conclusions:

• This study provides the first description of MR imaging features for pediatric diffuse midline gliomas with histone H3 K27M mutation.
• The imaging appearance of these mutated gliomas is diverse and not distinguishable from histone H3 wildtype diffuse gliomas.