Abstracts

Rationale: Dysembryoplastic neuroepilthelial tumours (DNETs) are part of a group of glioneuronal tumours which are considered to have a stable size and clinical progression. The latest 2007 World Health Organization (WHO) classification of tumours of the central nervous system reported that long-term clinical follow-up usually demonstrates no recurrence. More recently, there have been a few case reports and a small case series describing tumour recurrence and transformation.Methods: We report on an unusual case of a 20 year old man with a parietal DNET which recurred as a pilocytic astrocytoma three years after resection. Results: The patient first presented with focal seizures when he was six years old and had a mild right hemiparesis. MRI brain showed a mass lesion in the medial aspect of the left parieto-occipital lobe. His epilepsy was resistant to treatment having been on seven antiepileptic drugs. Due to the extent of the lesion which involved eloquent areas of brain relating to visual and motor pathways, a surgical option was not pursued. The size of the lesion remained stable. However, at the age of 14, the patient presented with an acute encephalopathy following haemorrhage of DNET with intraventricular extension. A craniotomy for evacuation of the haematoma was performed along with biopsies of the lesion. The histology was consistent with a DNET. Three years later, he represented with a subacute history of headaches and neurological deterioration. CT brain showed a heterogenous cystic space-occupying lesion in the same region. The patient underwent craniotomy and debulking of the lesion followed by a course of radiotherapy. The histological appearance of this latter lesion was classified as a predominantly WHO Grade I pilocytic astrocytoma without any obvious features of a residual DNET. Currently, the patient is progressing well and has shown improvements in his interval neuroimaging.Conclusions: This case report adds to the growing view that DNETs have the capacity for regrowth and transformation. Prospective studies with long-term surveillance in resected as well as non- resected DNETs may help to guide us in understanding the clinicopathological nature of these tumours.