title: Ewing's sarcoma. A light- and electron-microscopic study of 21 cases.
abstract: Twenty-one cases of Ewing's sarcoma were analyzed by light- and electron-microscopy and the fine structure compared to that described in previous publications. In the predominant "primary" tumor cells, glycogen was abundant in 53% of cases, infrequent in 33%, and rare in 14%. In three cases, microtubules, in association with glycogen, were demonstrated. The so-called differentiated "secondary" reticular tumor cells were sparsely populated in eight cases. Evidence is presented to suggest that these so-called "secondary" reticular cells are merely "primary" tumor cells in a state of regression. Secondary cells and cells with nuclear identations or convolutions were of no discernible prognostic significance. The histogenesis of Ewing's sarcoma remains an enigma but present findings support a primitive mesenchymal origin.
mesh_terms: D000293:Adolescent; D000328:Adult; D001859:Bone Neoplasms / Q000473:pathology* / Q000628:therapy / Q000648:ultrastructure; D002648:Child; D005121:Extremities; D005260:Female; D006003:Glycogen / Q000032:analysis; D006801:Humans; D008297:Male; D008870:Microtubules / Q000648:ultrastructure; D010384:Pelvic Bones; D012272:Ribs; D012512:Sarcoma, Ewing / Q000473:pathology* / Q000628:therapy / Q000648:ultrastructure
chemical_list: D006003:Glycogen