A case of dysembryoplastic neuroepithelial tumor of the parietal lobe with characteristic magnetic resonance imaging.

The case of a 4 year old boy with a dysembryoplastic neuroepithelial tumor (DNT) of the left parietal lobe is reported. The DNT was located mainly in the cortex and showed no mass effect on magnetic resonance imaging (MRI). T1-weighted images of the DNT showed the characteristic findings of lesion hypointensity, but with a well preserved gyrus-like configuration. This lesion was isointense to the normal cortex on proton density imaging and hyperintense on T2-weighted imaging. The characteristic features on T1-weighted and proton density imaging in this patient were useful in differentiating DNT from other types of tumors. Histologic findings in DNTs, which include the presence of both glial and neuronal cells without atypia and no definite transitional zone between the adjacent disorganized cortical cell layers, suggest that DNT is not a true neoplasm but rather a dysplastic lesion. It is clinically important to differentiate this tumor both from other benign tumors and malignant tumors which have different prognoses and therapies. The distinctive MRI findings, as well as the histologic features of DNT, support the diagnosis in the clinical setting.