UNUSUAL EVOLUTION: PROGRESSIVE DYSEMBRYOPLASTIC NEUROEPITHELIAL TUMOUR WITH ATYPICAL CONTRAST ENHANCEMENT AND MR SPECTROSCOPY ABNORMALITIES- A 10-YEAR FOLLOW-UP CASE REPORT

Abstract AIMS Dysembryoplastic neuroepithelial tumours (DNETs) are benign, slow-growing glial-neuronal tumours in chil- dren. Treatment includes surveillance and follow-up or surgical excision. DNETs do not typically demonstrate contrast enhancement on MRI. We describe a rare unusual radiological progression of a DNET case over a 10 year period. METHODS We present a 21-year-old female who was initially diagnosed with a left occipital DNET based on typical imaging findings and clinical presentation, when she had her first seizure at age of 11. RESULTS Over 10 years, the tumour remained stable on MRI, and seizures were well-controlled with Levetiracetam. Initial imaging in 2014 revealed a left occipital lesion with typical DNET characteristics: high T2 signal, low T1 signal, and no contrast enhancement. Annual surveillance MRIs from 2014 to 2022 showed no significant changes. However, the 2024 MRI demonstrated lesion progression, with irregular contrast enhancement, in- creased choline, reduced NAA and creatine, and a lactate peak on MR spectroscopy. Diffusion tensor imag- ing (DTI) revealed disruption of white matter tracts, further suggesting atypical behaviour. This concerning and atypical behaviour made us consider the possibility of an initial low-grade-glioma undergoing a malignant transformation. A gross total resection was achieved and histopathological and molecular analyses confirmed a benign DNET without BRAF, IDH1/IDH2 mutations, or MGMT promoter hyper methylation. CONCLUSION This case highlights the diagnostic challenges posed by DNETs with atypical imaging features, including con- trast enhancement and metabolic changes, which can mimic a high-grade transformation. Whilst advanced imaging techniques, such as MR spectroscopy, are critical in monitoring these tumours, this case underscores that current modalities are still not conclusive in defining tumour histology and warrant further radio-genomic research. Surgical resection not only provides definitive diagnosis but also guides long-term management in cases of radiological uncertainty.