Ewing's sarcoma. Cytologic features in fine needle aspirates in two cases.

The cytologic findings of two cases of Ewing's sarcoma in fine needle aspiration biopsies are presented in relation to the subsequent histologic findings. The malignant cells were arranged in monocellular layers, pseudorosettes and in perivascular palisades in a fibrillar background. The nuclei were monomorphous with small nucleoli and finely granular chromatin. These features may be helpful in distinguishing this tumor from other small-cell neoplasms; the differential diagnosis between Ewing's sarcoma and such tumors is discussed.