small , round , blue-cell tumors ( srct ) , including rhabdomyosarcoma , ewing 's sarcoma of bone and soft tissue , mesenchymal chondrosarcoma , small cell osteosarcoma , hemangiopericytoma , neuroblastoma , peripheral neurectodermal tumor ( peripheral neuroepithelioma of bone and soft tissue ) , and the malignant small cell tumor of the thoracopulmonary region described by askin ( askin 's tumor ) , are often difficult to distinguish by light microscopy .
C0585474
ewing 's
C0225317
soft tissue