Ewing's sarcoma of bone: clinicopathologic aspects of 303 cases from the Intergroup Ewing's Sarcoma Study.

Clinicopathologic features of 303 cases of Ewing's sarcoma of bone collected by the Intergroup Ewing's Sarcoma Study group are described. Ewing's sarcoma was found to arise predominantly in the inferior segment of the skeleton in young white patients from 10 to 15 years of age. Of the several recognized histologic patterns, the filagree pattern--an organoid pattern consisting of bicellular strands of tissue separated by filmy vascular stroma--was associated with the lowest survival rates. Light microscopic evidence of cytoplasmic glycogen in tumor cells was found to be useful in but not requisite for diagnoses. The most important predictor of clinical behavior, regardless of treatment modality, was the site of primary involvement. Survival among patients with primary tumors in pelvic bones was lowest, whereas survival among patients with lesions in distal bones of the extremities was highest.