ESWR1-CREM Fusion in an Intracranial Myxoid Angiomatoid Fibrous Histiocytoma-Like Tumor: A Case Report and Literature Review

: Gene fusions of EWSR1 with members of the CREB family of transcription factors (CREB1, ATF1, and CREM) have recently been described in exceptional intracranial myxoid mesenchymal tumors. Although this is a known gene fusion found in various mesenchymal tumors, EWSR1 fusion with CREM has only been observed in 3 intracranial myxoid tumors. In this paper, we present 1 such tumor with in-depth histopathological description and long-term follow-up. There is controversy regarding whether these tumors represent a novel entity or simply an intracranial localization of the myxoid variant of angiomatoid fibrous histiocytoma, a rare soft tissue tumor of the extremities. Out of 11 cases mentioned in the literature, the 3 isolated case reports by Dunham et al, Ochalski et al, and Alshareef et al are designated as angiomatoid fibrous histiocytoma, whereas the others are defined as a novel tumoral entity called intracranial myxoid mesenchymal tumor with EWSR1-CREB fusion. We believe the vast morphological and immunohistochemical spectrum of angiomatoid fibrous histiocytoma makes it difficult to dismiss this diagnosis.