Brain tumors are the second most common type of structural brain lesion that causes chronic
epilepsy. Patients with low-grade
brain tumors often experience chronic
drug-resistant epilepsy starting in childhood, which led to the concept of long-term
epilepsy-associated
tumors (LEATs). Dysembryoplastic
neuroepithelial tumor and
ganglioglioma are representative LEATs and are characterized by young age of onset, frequent temporal lobe location, benign
tumor biology, and chronic
epilepsy. Although highly relevant in clinical epileptology, the concept of LEATs has been criticized in the neuro-oncology field. Recent genomic and molecular studies have challenged traditional views on LEATs and low-grade
gliomas. Molecular studies have revealed that lowgrade
gliomas can largely be divided into three groups : LEATs, pediatric-type diffuse low-grade
glioma (DLGG;
astrocytoma and
oligodendroglioma), and adult-type DLGG. There is substantial overlap between conventional LEATs and pediatric-type DLGG in regard to clinical features, histology, and molecular characteristics. LEATs and pediatric-type DLGG are characterized by mutations in BRAF, FGFR1, and MYB/MYBL1, which converge on the RAS-RAF-MAPK pathway. Gene (mutation)-centered classification of epilepsyassociated
tumors could provide new insight into these heterogeneous and diverse
neoplasms and may lead to novel
molecular targeted therapies for
epilepsy in the near future.