MLS/RCLS carry a rearranged DDIT3 fused to FUS or EWSR1 [5, 6]. DDIT3 is expressed and involved in the regulation of adipocyte development and we have previously shown that expression of DDIT3 in a low differentiated fibrosarcoma cell line results in morphological conversion towards a liposarcoma phenotype [7]. Here, DDIT3 is linked to fibrosarcoma.