Dysembryoplastic neuroepithelial tumors (DNETs)

In 1988, Daumas-Duport described a surgically curable tumor highly associated with intractable partial epilepsy and normal neurologic examination.29 The temporal cortex was the location of 62% of these tumors, with 31% in the frontal cortex(see Figure 3). Case reports have described DNETs to occur in multifocal areas, including the caudate nuclei, midbrain, and diencephalon.29,146,147

Histologically, DNETs are composed of neurons, astrocytes, and oligodendrocytes (see Figure 9). Immunohistochemistry for glial fibrillary acidic protein (GFAP), S-100 protein, and neuronal markers synaptophysin, neurofilament (RT97), and neuron-specific enolase establish the presence of astrocytic and neuronal components, while GFAP reactivity is negative for an oligodendrocytic component.148,149

Figure 9. Dysembryoplastic neuroepithelial tumor (DNET). 200x Intracortical nodule of variably sized oligodendroglial-like cells and disordered neurons demonstrating microcyst formation.

Although questions remain regarding the origin of this tumor, they may have a germinal origin.29,146,147

Treatment and prognosis

At the time of resection, patients’ ages ranged from 3 to 30 years, and patients presented with a longstanding history of symptoms, ranging from 2 to 18 years.29 Patients should be treated with gross total resection and considered cured after surgery.29,149,150 In the series by Daumas-Duport, 30 of 39 patients were seizure free postoperatively, 3 had rare seizures, and 4 had significant reductions in seizures.

Radiation and chemotherapy have not demonstrated a clear benefit, and withholding adjuvant therapy for this type of tumor prevents future deleterious side effects.29

Rarely, these tumors (as well as gangliogliomas) may be associated with a rare postoperative disorder, with schizophreniform features of paranoia, depression, and psychosis. This psychosis does not seem to accompany other tumor types resected for intractable epilepsy.151,152

Adapted from: Mangano FT, McBride AE, and Schneider SJ. Brain tumors and epilepsy. In: Ettinger AB and Devinsky O, eds. Managing epilepsy and co-existing disorders. Boston: Butterworth-Heinemann; 2002;175–194.
With permission from Elsevier (www.elsevier.com).
Reviewed and revised March 2004 by Steven C. Schachter, MD, epilepsy.com Editorial Board.