PERIPHERAL PRIMITIVE NEUROECTODERMAL TUMORS IN ADULTS - DOCUMENTATIONBY MOLECULAR ANALYSIS

Purpose: The Ewing tumor (ET) family of peripheral primitive neuroecto dermal rumors (pPNETs) are primitive small round-cell tumors (SRCTs) o f the bone and soft tissue that occur predominantly in children and ad olescents, However, pPNETs only rarely enter the differential diagnosi s of bone and soft tissue SRCTs in adults, Recently, gene fusions betw een the EWS gene and different members of the ETS transcription factor family have been shown to occur in virtually all pPNETs and thus cons titute a pathognomonic marker for this tumor subclass. The aim of the present study was to document EWS/ETS fusion gene expression in suspec ted pPNETs of adults as objective evidence for the existence of this t umor family in older patients. Patients and Methods: The three contrib uting molecular diagnostic laboratories retrospectively compiled a coh ort of all SRCT cases in which EWS/ETS gene fusions had been shown by molecular analysis. This cohort was surveyed for cases that occurred i n patients aged 40 years or older, which were then analyzed for their clinical and pathologic features. Results: Nine patients between 40 an d 65 years of age were found to have tumors positive for EWS/ETS gene fusions. Standard histopathologic and clinical features of these cases , other than age, were similar to those of childhood pPNETs, Patients were initiated on appropriate therapy after molecular analysis confirm ed the diagnosis of pPNET. Conclusion: Identification of an EWS/ETS ge ne fusion is useful in providing objective evidence of the diagnosis o f pPNET in patients over the age of 40 years, This diagnosis should be considered in adults who present with bone and soft tissue SRCTs and appropriate biopsy specimens should be collected for molecular analysi s at the time of diagnosis. (C) 1998 by American Society of Clinical O ncology.