Intracranial Myxoid Mesenchymal Tumor with Rare EWSR1-CREM Translocation.

Translocations between EWSR1 and members of the CREB family of transcription factors (CREB1, ATF1, and CREM) are rare genetic findings occurring in various sarcomas. Of these, the EWSR1-CREM translocation is the most rarely reported. We present the case of a 9-year-old boy who presented with a year of fatigue, weight loss, and abulia. A brain MRI revealed a frontal interhemispheric tumor arising from the falx. After resection, pathology demonstrated a myxoid mesenchymal tumor with an EWSR1-CREM translocation. A series of recent reports of similar tumors has generated ongoing debate in the literature over the classification of these tumors either as intracranial angiomatoid fibrous histiocytomas, which also harbor EWSR1-CREB family translocations, or as a novel diagnostic entity. The present case provides another example of the rare EWSR1-CREM fusion in an intracranial myxoid mesenchymal tumor that recurred in just 6 months despite gross total resection. The findings are discussed in the context of the existing literature and the ongoing effort to appropriately classify this type of tumor.