Clinicopathological analysis of EWSR1/FUS::NFATC2 rearranged sarcoma in the left forearm:A case report

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.