A clinicopathologic study of 20 cases of large-cell (atypical) Ewing's sarcoma of bone.

A review of 347 Ewing's tumors that were seen at the Mayo Clinic during the period to the end of 1978 revealed 20 that differed histologically from the remainder. These 20--called "large-cell Ewing's tumor"--differed from the classic Ewing tumor in having larger, more pleomorphic cells, often with conspicuous nucleoli. More males than females had such tumors, and most patients were in the second decade of life. The diaphysis of long bone was commonly involved. The radiologic appearance was that of a permeative lesion. This large-cell Ewing tumor may be confused with malignant lymphoma and small-cell osteosarcoma. In the present study, there was no apparent difference in the clinical behavior of large-cell and typical Ewing's tumors.