Intracranial myxoid mesenchymal
tumors (IMMTs) with EWSR1-CREB1 family gene fusion are rare
brain neoplasms characterized by gene fusion between the EWSR1 gene and one of the
cyclic AMP response element-binding (CREB) family
transcription factor (CREB1, ATF1, or CREM) genes. Although half of reported cases are pediatric, the clinical, histologic, and genomic features of IMMTs with EWSR1 rearrangement in pediatric populations are not yet well clarified. Here we describe the case of a 7-year-old girl who presented with
seizures due to an extra-axial
tumor in the left parietal convexity. Gross total resection was achieved, and the
tumor displayed a multilobular structure with solid hypercellular and myxoid hypocellular areas, separated by a variable amount of stroma. The hypercellular areas consisted of round to polygonal cells, whereas the myxoid areas were ovoid to spindled cells. Immunophenotypically, the
tumor cells were positive for
vimentin,
desmin, and EMA. Next-generation sequencing of tumoral
DNA revealed EWSR1-CREM gene fusion and a pathogenic mutation of MAP3K13. No recurrence was detected 9 months after resection, without
chemotherapy or
radiotherapy. In comparison to other pediatric and adult patients with EWSR1 rearrangement, many clinical, radiological, and immunohistochemical features were shared. However, signs of
elevated intracranial pressure were more frequently observed, and postoperative radiation was less frequently administered for pediatric patients. Gross total resection (GTR) was the key prognostic factor for better disease control especially among pediatric patients. Further reports of cases with EWSR1 rearrangement with detailed genetic profiles are essential for clarifying the oncogenic pathway and establishing a standard treatment strategy.