Ewing sarcoma 2013-04-07T01:54:14Z Histologically, Ewing's sarcoma is composed of a homogeneous population of small round cells with high nuclear to cytoplasmic ratios that are arrayed in sheets. There is scant cytoplasms, which is pale, vacuolated and characterized by faded boundaries. In contrast, the nuclei are clearly visualized by their intense color. Mitotic activity is typically low. HP:0012254 A malignant tumor of the bone which always arises in the medullary tissue, occurring more often in cylindrical bones. SNOMEDCT_US:76909002 Ewing's sarcoma UMLS:C0553580 Sarcoma