A dysembryoplastic neuroepithelial tumor (DNET) is a glioneuronal tumor that is cortically based, usually with a multinodular and/or multicystic appearance. Histologically, DNET's are characterized by oligodendrioglial like cells, intermixed with neuronal and astrocytic cells, with minimial cellular atypia. They are commonly found in the temporal lobes, but can be found elsewhere. They are frequently found to co-occur with adjacent focal cortical dysplasia (FCD IIIb), suggesting a common developmental etiology for both structural abnormalities.
The clinical presentation of a DNET depends on the location of the tumor, and co-occurring structural abnormalities (such as focal cortical dysplasia, hippocampal sclerosis). Seizures occur in almost all patients. Onset of seizures can be at any age, but is most commonly in childhood. Seizures are typically uncontrolled by medication. Both sexes may be affected, but a male predominance has been reported. Patients do not initially suffer from significant developmental, neurological or cognitive impairment, but this can occur in association with uncontrolled seizures. Psychiatric disorders have been reported in individuals with DNET.
CAUTION developmental and cognitive outcome may be worse in children with uncontrolled seizures in early life, especially if epileptic spasms or generalized seizure types appear, therefore proactive seizure control is important in these patients.
CAUTION as epilepsy surgery is expected to be associated with a high chance of permanent seizure freedom, this should be pursued in a timely fashion if seizures are uncontrolled with medication, if there are emerging developmental, cognitive or psychiatric impairments, or if generalized seizure types are seen.