Abstract
BACKGROUND: We present a case of an EWSR1/FUS::NFATC2 rearranged sarcoma in the left forearm and analyze its clinicopathological and molecular features. CASE SUMMARY: The patient is a 23-year-old woman. Microscopically, the tumor cells were medium-sized round cells arranged in small nests. The cytoplasm was clear, nuclei were relatively uniform, chromatin was dense, nucleoli were visible, and mitotic figures were rare. Immunohistochemically, the tumor cells were positive for Vimentin, INI-1, CD99, NKX2.2, CyclinD1, friend leukaemia virus integration 1, and NKX3.1. Next-generation sequencing revealed the presence of the EWSR1-NFATC2 fusion gene. EWSR1/FUS::NFATC2 rearranged sarcomas are rare and can easily be misdiagnosed. CONCLUSION: Clinical imaging, immunohistochemistry, and molecular pathology should be considered to confirm the diagnosis.