Primary vulvar Ewing sarcoma/primitive neuroectodermal tumor: a report of 2 cases and review of the literature.

Ewing sarcoma/primitive neuroectodermal tumor (ES/PNET) family of tumor is a very aggressive malignant round cell tumor characterized by translocations involving EWS-FLI1 genes. They are increasingly recognized in extraosseous sites as a result of improvements in diagnostic tools. In this paper, we report 2 additional cases arising in vulva of young adults who have been treated aggressively and have survived fore more than 7 and 4 years successively. Histologic examination showed small round (blue) cell morphology in both cases. The tumor cells contained glycogen and were positive for CD99 and vimentin and negative for keratins, lymphoid markers, S-100, synaptophysin, chromogranin, and desmin. Reverse transcriptase polymerase chain reaction analysis from paraffin-embedded tissue revealed EWS-FLI1 fusion product in 1 case. Collectively, 13 cases of vulvar ES/PNET have been reported in the literature. Only 8 cases have detailed follow-up information with an average follow-up data of 28 months. Ewing sarcoma/PNET should be considered in the differential diagnosis of any undifferentiated tumors involving the lower gynecologic tract and all axillary tests including molecular tests should be performed for correct diagnosis because prolonged survival is possible for this dreadful disease after complete surgical resection, followed by adjuvant therapy.