Neuroradiology

Dysembryoplastic neuroepithelial tumour

(DNET), an uncommon, slow-growing superficial hemispheric lesion found mainly in young adults. Due to the slow growth, the cortical location (usually in the temporal lobe) and the frequent presence of cysts, skull remodelling with erosion of the inner and middle table is frequently found in association. The most common clinical presentation is partial complex seizure disorder. Microscopically the nodules contain oligodendroglial hypercellularity and cortical dysplasia is frequently associated.

At CT and MR (Fig.1) the nodules are slightly hypointense with respect to cortex at CT, particularly if they contain cysts, and have long T1 and T2 at MR; enhancement is usually absent. Calcifications may be present.

GS

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Fig.1

a. MR, IR coronal image. The posterior part of the first frontal convolution is abnormal, slightly expanded, with inhomogeneous hypointense signal. b. MR axial FLAIR image. The precise posterior frontal premotor location of the lesion is well appreciated. Signal is inhomogeneous indicating presence of cystic components as well as solid. c. MR, sagittal T2-weighted image. The tumour is mainly hyperintense. d. MR, sagittal T1-weighted image following gadolinium injection. Some enhancement is seen in the deepest part of the tumour.
Dysembryoplastic neuroepithelial tumour, Fig.1 (a)
Dysembryoplastic neuroepithelial tumour, Fig.1 (b)
Dysembryoplastic neuroepithelial tumour, Fig.1 (c)
Dysembryoplastic neuroepithelial tumour, Fig.1 (d)