Visceral primitive peripheral neuroectodermal tumors: A clinicopathologic and molecular study

Ewing sarcoma-primitive neuroectodermal tumor (EWS/PNET) belongs to the gro up of pediatric small round blue cell tumors; although EWS/PNET is classica lly a tumor of the soft tissue or bone in children and young adults, indivi dual cases have been described in patients of all ages. A group of chromoso mal translocations involving the EWS gene and a member of the Ets transcrip tion factor family of genes has been detected in EWS/PNET, and heterogeneit y in the precise breakpoint of the translocation has been shown to generate a group of related fusion transcripts that may have prognostic significanc e. Within the last decade, the clinicopathologic spectrum of EWS/PNET has b een markedly expanded by recognition that the tumor may also have a viscera l origin. To determine whether visceral EWS/PNET has the same pattern of ge netic alterations and range of fusion transcripts as EWS/PNET of bone and s oft tissue, we performed reverse-transcription polymerase chain reaction-ba sed testing of formalin-fixed, paraffin-embedded tissue from a series of vi sceral tumors for which the diagnosis of EWS/PNET was well established. Tog ether with additional cases compiled from the literature, EWS-Fli1 (or a re lated fusion transcript) was present in 18 of 19 visceral EWS/PNET, with a distribution of transcript types not statistically different from EWS/PNET of soft tissue and bone (P > .05, chi (2) test). These results firmly estab lish the genetic relationship between EWS/PNET of visceral sites, soft tiss ue, and bone. Hum PATHOL 32:1109-1115. Copyright (C) 2001 by W.B. Saunders Company.