Ewing’s Sarcoma / Peripheral Primitive Neuroectodermal Tumor (ES/PNET) Differentiation in Endometrial Serous Carcinomas

The association of Ewing's sarcoma/peripheral neuroectodermal tumor and endometrioid type endometrial carcinoma has been reported relatively recently. We have recently identified Ewing's sarcoma/peripheral neuroectodermal tumor differentiation in uterine serous carcinomas and undertook this study to evaluate the frequency of both serous and endometrioid carcinomas expressing Ewing's sarcoma/peripheral neuroectodermal tumor differentiation. Seventy cases of uterine serous carcinoma were retrieved from the archival files and stained with antibodies to CD99. Positive and negative control slides were run with each staining batch. Perinuclear dot-like and/or membranous staining was regarded as positive. The frequency of Ewing's sarcoma/peripheral neuroectodermal tumor differentiation in 56 FIGO grade 3 endometrioid carcinomas was also determined and 7% uterine serous and 12.5% of FIGO grade 3 endometrioid endometrial carcinomas showed Ewing's sarcoma/peripheral neuroectodermal tumor differentiation. Given the ...