What to know in a case of Dysembryoplastic Neuroepithelial Tumor (DNET) of brain

Clinical History

A 12-year-old male presented with complaints of convulsion for the last year.
He also had a history of developmental delay for the last 4 years. He was referred for MRI Brain study to rule out intracranial pathology.

Imaging Findings

The study reveals evidence of a small well-defined altered signal intensity “bubbly” appearing cortical based mass lesion at right parasagittal anterior frontal lobe. The lesion demonstrates CSF signal intensity in T1W, T2W, FLAIR and T1 Inversion Recovery images (Fig.1, 2, 5). No evidence of perifocal oedema, intralesional calcification or haemorrhage noted (Fig.4). Diffusion weighted images do not reveal any diffusion restriction (Fig.3).

The post-contrast study does not reveal abnormal enhancement of the above described lesion (Fig.7, 8).

Discussion

Dysembryoplastic neuroepithelial tumours (DNET) are benign slow growing tumours classified as a WHO grade I tumour. DNET was first proposed as a specific entity by Daumas-Duport et al. in 1988. They are cortically based tumours usually arising from grey matter. They are most commonly located in the temporal lobe (over 50-60% of cases) and frontal lobe (20- 30% of cases), but all parts of the CNS containing grey matter such as caudate nucleus, cerebellum and pons can be affected [1].

Patients with this tumour present with complaints of headache and symptoms and signs of complex partial seizures.These tumours are usually diagnosed in children or young adults [1, 2].

Radiological findings on MRI include multiple T1-hypointense and T2-hyperintense “pseudocystic” areas of different sizes which gives a 'bubbly' appearance. On FLAIR it appears hypointense, which differentiates it from multinodular and vacuolating neuronal tumours. On diffusion weighted images it does not show restricted diffusion. Peritumoural oedema, calcification, midline shift or significant contrast enhancement is not typical. MR spectroscopy may aid diagnosis, with findings including non elevation of the ratio of choline-containing compounds to creatine, normal creatine peak and low N-acetylaspartate peak. Final diagnosis is confirmed histologically. One of the main differential is a multinodular and vacuolating neuronal tumour which is a recently described subcortically based low grade tumour which does not suppress on FLAIR [1-4].

Treatment includes symptomatic management of convulsion and headache. Surgical resection is required only in cases of refractory seizures [1-3].

Prognosis is very good. These tumours remain stable without any further growth in most cases. Even if it increases in size, it shows very slow growth.

Differential Diagnosis List

Final Diagnosis

Dysembryoplastic Neuroepithelial Tumor (DNET)

URL:	https://www.eurorad.org/case/14337
DOI:	10.1594/EURORAD/CASE.14337
ISSN:	1563-4086