A dysembryoplastic neuroepithelial tumor (DNET) is a rare, benign brain tumor that primarily affects children and young adults. It is classified as a low-grade tumor, meaning it grows slowly and generally has a favorable prognosis. The exact cause of DNETs is not fully understood, but they are believed to arise from abnormal development of the brain’s neuroepithelial cells during early brain formation.
DNETs are thought to originate from embryonic cells that fail to mature properly, leading to a tumor composed of a mixture of neuronal and glial elements. This abnormal development likely occurs during fetal brain formation, which is why these tumors are often considered developmental or congenital in nature. Unlike many malignant brain tumors caused by acquired genetic mutations later in life, DNETs seem to result from a disruption in the normal process of brain tissue differentiation and organization.
At the molecular level, some DNETs have been found to harbor mutations in specific genes, such as the BRAF gene, particularly the BRAF V600E mutation. This mutation affects a protein involved in cell growth and division, potentially contributing to the abnormal proliferation of cells within the tumor. However, not all DNETs carry this mutation, and the presence of BRAF mutations is more of a marker associated with the tumor rather than a definitive cause. The role of these genetic changes in the initial formation of DNETs remains an area of ongoing research.
The tumor typically develops in the cerebral cortex, the outer layer of the brain responsible for many higher functions, and is often associated with epilepsy. The seizures caused by DNETs are thought to arise because the tumor disrupts the normal electrical activity of the brain tissue around it. This disruption may be due to the tumor’s interference with the local neuronal networks or changes in the microenvironment that increase neuronal excitability.
Unlike high-grade malignant tumors that cause seizures through aggressive invasion, necrosis, or inflammation, DNETs cause seizures primarily because of their location and the way they alter the surrounding brain tissue’s function. The slow-growing nature of DNETs means they often cause chronic, drug-resistant epilepsy, which is sometimes the first sign leading to their diagnosis.
In summary, DNETs are caused by developmental abnormalities in the brain’s neuroepithelial cells during embryogenesis, possibly influenced by genetic mutations like those in the BRAF gene. Their growth disrupts normal brain circuits, leading to seizures. The exact triggers and pathways that cause these tumors to form remain incompletely understood, but they are distinct from the mechanisms underlying more aggressive brain tumors.
