Diffuse hemispheric glioma, H3G34 mutant (DHG) is a rare, high-grade, infiltrative WHO grade 4 brain tumor most often found in adolescents and young adults. The majority are found in the frontal, parietal, and

temporal lobes The temporal lobe is one of the four Lobes of the brain, major lobes of the cerebral cortex in the brain of mammals. The temporal lobe is located beneath the lateral fissure on both cerebral hemispheres of the mammalian brain. The temporal lobe ...

Diagnosis

Prior to 2021, most DHG's fell into the classification of Glioblastoma (GBM). However, modern sequencing techniques have revealed that the molecular alterations driving the cancer are entirely distinct to GBM, leading to changes in the World Health Organization classification system. They are further distinguished from GBM by their radiological presentations, including no or faint

contrast enhancement A contrast agent (or contrast medium) is a substance used to increase the contrast of structures or fluids within the body in medical imaging. Contrast agents absorb or alter external electromagnetism or ultrasound, which is different from radioph ...

. A diagnosis can only be definitively made with genetic testing of the tumor.

Treatment

Available treatment for DHG will vary depending on the location in the brain that the tumor arises, but typically the first stage of treatment is surgical resection, with the aim of removing as much of the tumor as possible (i.e. gross- or near-total resection). Concomitantly, patients will undergo radiotherapy or proton therapy. Following this, patients will undergo chemotherapy, most commonly with Temozolomide.

Prognosis

Median time to progression is 10 months. After progression, the median time to death is 5 months. Non-pediatric patients and patients with near-or-gross total resection have increased survival duration.

Pathology

Diffuse hemispheric gliomas have a distinct mutation in the histone gene H3F3A.

References

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External links

Radiopaedia
Nervous system neoplasia