What's new in Ewing's tumor?

Ewing's tumor is an undifferentiated neoplasm that has eluded many attempts at classification since it was first described in 1919. Even modern techniques applied to the study of series of tumors with clinical and pathologic features of Ewing's tumor have not elucidated its histogenesis. Some of these studies conclude that the cell of origin of Ewing's tumor may be a noncommitted mesenchymal cell, but many other studies suggest a neuroectodermal differentiation and further results indicate a primitive, pluripotential cell for Ewing's tumor that may differentiate in mesenchymal, epithelial and neural features. Consequently, this tumor should be regarded as a blastoma.