the existence of a morphological diversity within the ewing 's sarcoma group allows the authors to differentiate a conventional form of ewing 's sarcoma ( 21 cases ) consisting of principal blastemic cells and secondary degenerative ones ( dark cells ) from an atypical variant ( 7 cases of atypical ewin 's sarcoma ) whose structure adopts either an immature mesenchymal or histiocytic appearance .
C0553580
ewing 's sarcoma
C1261473
sarcoma