Ewing's sarcoma and peripheral primitive neuroectodermal tumor: an interim report.

The primitive neuroectoderm and its progeny seemingly give rise to an ever-increasing number of clinicopathologic entities. Ewing's sarcoma and peripheral primitive neuroectodermal tumor have recently been united by relatively unique antigens expressed by the MIC-2 gene, commonly coexpressed neural markers, and cytogenetic and molecular genetic abnormalities. Because of these factors, the current thinking is that Ewing's sarcoma and the peripheral primitive neuroectodermal tumor are parts of a phenotypic spectrum. We present an "interim report" on this group of neoplasms, emphasizing their presentation in the head and neck.