Differential expression of WT-1 in serous carcinomas in the peritoneum with or without associated serous carcinoma in endometrial polyps

Although differential WT-1 expression between ovarian and uterine serous carcinoma has been discussed in the literature, there have been no studies of WT-1 expression in serous carcinomas in the peritoneum with or without concurrent serous carcinoma in an endometrial polyp. This study addresses this issue and includes a small series of uterine and ovarian serous carcinomas for comparison. Nine peritoneal serous carcinomas with coexistent serous carcinoma in an endometrial polyp, 10 peritoneal serous carcinomas without serous carcinoma in an endometrial polyp, 9 uterine serous carcinomas, and 12 ovarian serous carcinomas were stained with antibody to WT-1. Ninety-two percent of ovarian serous carcinomas and 80% of peritoneal serous carcinomas without serous carcinoma involving an endometrial polyp expressed WT-1. In contrast, 12% of peritoneal serous carcinomas with serous carcinoma in an endometrial polyp expressed WT-1 with the serous carcinoma in the endometrial polyp staining concordantly. For uterine serous carcinoma without an endometrial polyp, only 11% expressed WT-1. Peritoneal serous carcinomas without coexistent serous carcinoma in an endometrial polyp have a WT-1 expression pattern similar to ovarian serous carcinoma while peritoneal serous carcinomas with coexistent serous carcinoma in an endometrial polyp have a staining pattern similar to uterine serous carcinoma. The difference in WT-1 expression among serous carcinomas suggests a difference in biology based on the site of origin. Additionally, the difference in WT-1 expression between peritoneal serous carcinomas with and without coexistent serous carcinoma in endometrial polyps suggests that peritoneal serous carcinoma may have different pathogenetic pathways.