In conclusion, NKX2.2, ETV4 and BCOR IHC may be helpful in daily practice for distinguishing ESFT from CIC or BCOR-associated sarcomas, especially in hospitals without access to molecular assays.
Unsupervised clustering by RNAseq data revealed that tumors with BCOR genetic alterations, including BCOR-CCNB3, BCOR-MAML3, and BCOR ITD, formed a tight genomic group distinct from ES and CIC-rearranged sarcomas.
In light of morphologic features that overlap with those of NC from typical anatomical sites we have seen previously, the tumor was best classified as falling within the NC spectrum rather than CIC-associated sarcoma.
The CIC-DUX4 sarcoma is a small round blue cell sarcoma which presents like extraskeletal Ewing sarcoma, but is negative for the EWSR1 gene translocation.