Atypical presentation of dysembryoplastic neuroepithelial tumor in an adult without epilepsy: a case report.

Dysembryoplastic neuroepithelial tumor (DNET) is a rare glioneuronal tumor usually found in the temporal lobe of children and young adults. DNETs are commonly associated with drug-resistant partial seizures, with most cases diagnosed before age 20. Asymptomatic brain tumors are rare in the general healthy population, and the frequency of incidental DNETs in adults remains unknown. We report the case of a 34-year-old healthy man who presented with a facial rash but was incidentally found to have a large T1 hypointense lesion in the left temporal cortex on neuroimaging. The patient opted for surgical removal of the mass, which was subsequently identified as a DNET, positive for a fibroblast growth factor receptor (FGFR) mutation. This case report presents the first incidentally discovered DNET in an adult without epilepsy, highlighting its atypical presentation. In addition, the presence of an FGFR mutation emphasizes its role in DNET pathogenesis and potential therapeutic implications. DNETs exhibit varied behavior based on age, tumor location, and cortical dysplasia. In this case, the absence of seizure onset may be attributed to the lack of cortical dysplasia. Further research is needed to understand the incidence of DNETs and their association with seizure onset and cortical dysplasia.