A lytic lesion with soft-tissue extension in the sacrum of a 47-year-o
ld man was needle-biopsied under computed tomographic (CT) guidance us
ing an 18-gauge cutting needle. The cytologic appearance of the lesion
and immunohistochemical staining were diagnostic of Ewing's sarcoma.
Specifically, a new marker (O13) for the presence of glycoprotein p30/
32 mic2 in Ewing's sarcoma was utilized.