Dysembryoplastic neuroepithelial tumor

Incidence

This tumor is extremely rare.

Origin

DNET was first described in 1988 and was recently included in the WHO classification. The origin is mixed glial-neuronal.

Macroscopic appearance and general characteristics

DNET is a supratentorial intracortical tumor, with possible cystic change and calcification. The majority of the lesions are located in the temporal lobe. It is usually associated with chronic epilepsy in children. It corresponds to Grade I.

Microscopic appearance (images 2 - 3)

DNET is a benign, predominantly intracortical lesion with a heterogeneous cellular composition, composed mainly of a population of oligodendrocyte-like cells with admixtures of mature ganglion cells and astrocytes, located in a myxoid or dense neurofibrillary matrix. There is a typical multinodular architecture. Differentiation from ganglioglioma is based on the multinodular architecture, the myxoid matrix and the predominant population of oligodendrocytes.

Imaging features (see case reports)

- CT scan

On non-contrast scans the lesion is hypodense, with evidence of cystic lesions in over 50% of the cases. Calcification is possible (20%). Enhancement is poor.

- MRI

Classically, prolonged T1 and T2 times are described, findings seen in most brain tumors.

A typical feature of DNET is its multicystic nature, which should correspond to the myxoid matrix and the multinodular architecture. The intensity of the fluid content of the cysts is higher than CSF on T1 and proton density images, due to its higher protein content.

Approximately half of the solid DNET elements show contrast enhancement (image 4).

Differential diagnosis

Differential diagnosis from low grade astrocytoma, oligoastrocytoma or ganglioglioma can be difficult.

Case report

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Dysembryoplastic neuro-epithelial tumor

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