Dysembryoplastic Neuroepithelial Tumor: A Benign but Complex Tumor of the Cerebral Cortex

Abstract

Dysembryoplastic neuroepithelial tumor (DNET) is a distinct type of low-grade glioneuronal tumor. Clinically, DNET is highly associated with intractable epilepsy in young children and adolescents. Therefore, the burden of the tumor comprises oncological concerns (recurrence), seizure control, and quality of life. The pathology of DNET is characterized by glioneuronal elements and floating neurons. Grossly, many DNETs harbor separate nodules on the medial side of the mass. Some of the satellite lesions are bone fide tumor nodules that grow during the follow-up. Therefore, removing all satellite lesions may be important to prevent tumor progression. Seizure control is highly dependent on the complete removal of tumors, and the presence of satellite lesions also exerts a negative impact on seizure outcomes.

Keywords: Children; Epilepsy; Glioma; Recurrence; Seizure.

Fig. 1. Radiological features of dysembryoplastic neuroepithelial tumor. A and B: T1-weighted and T2-weighted magnetic resonance images of a 10-year-old girl who presented with recurrent focal seizures. A multinodular mass is located in the right middle frontal gyrus. C and D: T2-weighted axial and coronal images of a 12-year-old boy who came to the clinic for chronic epilepsy. A large tumor is situated in the insular and left inferior frontal lobes. There are several satellite lesions (yellow arrows) on the medial side of the mass, in the caudate nucleus and internal capsule.

Fig. 2. Scan view of the dysembryoplastic neuroepithelial tumor (H&E staining; ×12.5). The right side shows multinodular intracortical growth pattern (encircled by red dots).

Fig. 3. Typical histological and immunohistochemical findings of dysembryoplastic neuroepithelial tumor. A: A high-power view (H&E staining; ×400) shows glioneuronal elements (columns formed by bundles of axons lined by oligodendroglia-like cells [OLCs] and floating neurons in the multinodular growth pattern). B: Faint MAP2 expression in OLCs and marked expression in floating neurons (encircled by red dots) are noted (MAP2; ×200). C: OLIG2 is expressed in the OLCs (OLIG2; ×200). D: CD34 is negative in some cases. However, it can show variable expression (CD34; ×200).

Fig. 4. Diagram of the typical histological features of a dysembryoplastic neuroepithelial tumor (DNET). A: Multinodular pattern. B: Glioneuronal elements with floating neurons. C: Diagram of the DNET architecture. OLCs, oligodendroglia-like cells.

Fig. 5. Diagnostic criteria for DNET (according to the 2021 WHO classification). DNET, dysembryoplastic neuroepithelial tumor. Adapted from Piertsch et al. Central Nervous System Tumors (5th ed); 2021. p. 123-6, with permission of International Agency for Research on Cancer [18].