Coexisting Intraepithelial Serous Carcinomas of the Endometrium and Fallopian Tube: Frequency and Potential Significance

Abstract

Most serous adenocarcinomas involving both the endometrium and ovary are presumed to arise in the endometrium. Recently, serous tubal intraepithelial carcinoma (STIC) has been implicated in the pathogenesis of pelvic serous carcinoma. This study explored the potential relationship between STIC and uterine serous carcinoma. Twenty-two consecutive cases of serous carcinoma involving the endometrium were studied. In each case, fallopian tubes were submitted in toto according to the protocol for sectioning and extensive examination of the fimbriated end. Extent of the endometrial tumor and presence/absence of STIC were documented. Immunostaining for p53 and Wilms tumor-1 was performed on all cases with STIC. p53 mutation analysis was performed in a subset of matched STICs and endometrial tumors. Eleven cases showed concurrent endometrial and adnexal involvement, including 6 with endosalpingeal involvement; STIC was confirmed in 5. In all 5, the concurrent endometrial tumor was either noninvasive, or exhibited only superficial (<5%) myometrial invasion. In 2 cases, identical p53 mutations were shared by both tubal and endometrial lesions. This study shows that noninvasive, genetically related serous carcinomas may coexist in both tube and endometrium. As management of serous neoplasms is predicated on site of origin, we propose that the sectioning and extensively examining the fimbria protocol be applied to all endometrial serous carcinomas and that tumors with concurrent STIC be classified as a distinct subset of pelvic serous carcinomas pending a clearer understanding of tumor origin.