Rearrangements involving EWSR1 or FUS and NFATC2 were recently shown to characterize simple (solitary) bone cyst (SBC).1 Two separate series have been reported and of 18 cases that were successfully analyzed, 11 cases (∼60%) showed NFATC2 rearrangement with either FUS (6/11) or EWSR1 (5/11).1,2 SBC is an intramedullary, usually unilocular, cystic bone lesion lined by a fibrous membrane and filled with serosanguinous fluid.3 This lesion predominantly affects the long tubular bones during the first 2 decades of life and is more common in males. This evidence concerns the gene EWSR1 and bone disorder.