Sinonasal Ewing sarcoma misdiagnosed as recurrent glomangiopericytoma: Case report and literature review

We present the case of a patient with a sinonasal mass diagnosed as glomangiopericytoma on initial resection. The patient experienced multiple recurrences over ten years, undergoing endoscopic resection each time and ultimately adjunctive radiation therapy. Cytogenetic testing of the fourth recurrence was positive for FUS-ERG fusion, a genetic abnormality seen in a rare subset of Ewing tumors and the first case to be described in a sinonasal tumor. Given the emergence of new immunophenotyping, clinicians should exercise a low threshold for cytogenetic testing in cases where a tumor exhibits characteristics atypical of the initial pathological diagnosis.