Primitive neurectodermal tumors: a case of extraosseous Ewing's sarcoma of the small intestine and review of the literature.

This is a review of extraosseous Ewing's sarcoma (ES) which includes a new, extremely rare case. The literature was examined with respect to determining the locations of extraosseous ESs, the incidence per site and in total and the criteria which confirm the similarity between extraosseous and osseous ES. ES sites were detected in several organs and tissues, mainly in the trunk, extremities and the retroperitoneal region. Studies confirmed that osseous and extraosseous ES are identical chromosomally and histologically. ES of the small intestine, described here, has not been previously documented in the literature. Along with the other different documented sites, a new location of primary extraosseous ES is also reported here.