The discovery of recurrent BCOR ITDs defines a major oncogenic event in this childhood sarcoma with significant implications for diagnostic and therapeutic approaches to this tumour.
The Ewing sarcoma overall survival was not statistically different, although there was a trend for longer survival of patients with BCOR-CCNB3 sarcomas in the extremities.
In this review we discuss the main categories of undifferentiated round cell sarcoma, in relation to Ewing sarcoma and its molecular variants, with particular emphasis on the genetic and biologic features of recently described entities including desmoplastic small round cell tumor and CIC-DUX4 as well as BCOR-CCNB3-associated round cell sarcomas.
Finally, we show that CCNB3 immunohistochemistry is a powerful diagnostic marker for this subgroup of sarcoma and that overexpression of BCOR-CCNB3 or of truncated CCNB3 activates S phase in NIH3T3 cells.