Case Presentation:
A 10-year-old female presented with 3 weeks of progressively worsening nausea and vomiting was found to have a large complex partially solid, partially cystic intra-axial mass in the left temporal parietal lobe with internal calcifications and mild mass effect on computed tomography (CT), concerning for primary brain tumor.
Neurological examination demonstrated right-sided pronator drift but was otherwise unremarkable. Magnetic resonance imaging (MRI) revealed a left temporal parietal cortically based cystic lesion with a solid enhancing component with surrounding vasogenic edema (Fig A-B).
The patient underwent craniotomy for gross total resection. Histopathological analysis revealed a highly cellular spindle cell tumor with brisk mitotic activity, positive immunohistochemical staining for Olig2 and ATRX, and negative for GFAP (Fig C-F). DNA methylation profiling was consistent with a diagnosis of CNS high grade neuroepithelial tumor with MN1 alteration, confirmed on Next-Generation Sequencing (NGS) as a MN1-BEND2 fusion. Germline sequencing demonstrated an ATM heterozygous pathogenic variant (ATM c.103C>T). The patient remains disease free 8 months after diagnosis in the absence of adjuvant therapy.