FUS gene is associated with which soft tissue tumor?

• A. Myxoid liposarcoma
• B. Low grade fibromyxoid sarcoma
• C. Ewing sarcoma
• D. Synovial sarcoma

Answer: (B)

FUS gene rearrangements are a hallmark of a subset of soft tissue sarcomas, driven by specific fusion partners that define the tumor. In low-grade fibromyxoid sarcoma, the typical driver is a FUS-CREB3L2 fusion (often from t(7;16)(q33;p11)), which explains why this tumor classically harbors FUS alterations. This fusion acts as an abnormal transcription factor promoting tumor development, and LGFMS has characteristic features such as alternating fibrous and myxoid areas with a deceptively bland look but potential for late metastasis. Among the options, this makes low-grade fibromyxoid sarcoma the best-known association with FUS gene rearrangements. While myxoid liposarcoma can also involve FUS, it does so with a different partner (FUS-DDIT3), and the other two tumors are driven by distinct fusions (EWSR1-FLI1 in Ewing sarcoma and SS18-SSX in synovial sarcoma).