Peripheral neuroepithelioma with ganglion cells: report of two cases and review of the literature

Pathobiologic markers of the ewing sarcoma family of tumors: state of the art and prediction of behaviour

Over the past three decades, the outcome of Ewing sarcoma family tumor (ESFT) patients who are nonmetastatic at presentation has improved considerably. The prognosis of patients with metastatic disease at the time of diagnosis and recurrence after therapy remains dismal. Drug-resistant disease at diagnosis or at relapse remains a major cause of mortality among patients diagnosed with ESFT. In order to improve the outcome for patients with potential relapse, there is an urgent need to find reliable markers that either predict tumor behaviour at diagnosis or identify therapeutic molecular targets at the time of recurrence. An improved understanding of the cell of origin and the molecular pathways that regulate tumorigenicity in ESFT should aid us in the search for novel therapies for ESFT. The purpose of this paper is thus to outline current concepts of sarcomagenesis in ESFT and to discuss ESFT patterns of differentiation and molecular markers that might affect prognosis or direct future therapeutic development.

Peripheral primitive neuroectodermal tumor with postchemotherapy neuroblastoma-like differentiation

We report the case of an 11-year-old girl with a retroperitoneal tumor in the left upper quadrant. The girl was admitted to hospital with weight loss and a painless abdominal mass that on biopsy was diagnosed as a peripheral primitive neuroectodermal tumor/Ewing sarcoma (pPNET/EWS) of the soft tissue. The patient underwent chemotherapy followed by surgical resection of the tumor 5 months after diagnosis. The posttreatment residual viable tumor showed a morphologic appearance resembling a neuroblastoma. Interphase and metaphase fluorescent in situ hybridization (FISH) studies performed on the pretreatment and posttreatment samples showed the presence of a t(11;22) rearrangement resulting in EWSR1/FLI1 gene fusion consistent with pPNET/EWS in both specimens. This case is unusual in the sense of showing the typical gene fusion for pPNET/EWS both in the pretherapy sample with the typical morphological appearance of this tumor and in the posttherapy specimen showing neural differentiation suggestive of a neuroblastoma.