Serous tubal intraepithelial carcinoma (STIC) has been implicated in the pathogenesis of pelvic serous carcinoma. We hypothesized that, if this is the case, the frequency of STIC should be substantially lower in endometrial serous carcinomas, in nonserous gynecologic malignancies, and in benign gynecologic neoplasms than in ovarian or peritoneal serous carcinomas. From 2007 to 2009 the fallopian tubes of 342 consecutive gynecologic cases were entirely submitted for histology using the Sectioning and Extensively Examining the FIMbriated end protocol. This study included 300 of these cases (277 TAH-BSO, 23 BSO) after exclusion. The hematoxylin and eosin-stained slides from the fallopian tubes were independently reviewed by 2 gynecologic pathologists who were blinded to all other findings; disagreements were resolved by a third pathologist. Among 46 cases of ovarian malignancies, STIC was identified in 6 (18.8%) of 32 cases of serous carcinoma, but not in any other subtype. Similarly, STIC coexisted in 4 (14.3%) of 28 cases of endometrial serous carcinoma; however, no STIC was identified in any of the 74 cases of nonserous endometrial malignancies. STIC was identified in 2 (28.6%) of 7 cases of peritoneal serous carcinoma. No STIC was identified among 15 nongynecologic malignancies, 90 cases of benign conditions, and 27 cases of other conditions including 4 cases of cervical adenocarcinoma in situ and high-grade cervical intraepithelial lesions, 8 cases of endometrial atypical complex hyperplasias, and 15 cases of ovarian borderline tumors. In conclusion, the fallopian tube may be the origin of some pelvic serous carcinomas. Other possibilities that may explain the origin of pelvic high-grade serous carcinoma are discussed. Given that STIC coexisted with 14% of endometrial serous carcinomas, a more unifying theory may be that gynecologic serous carcinomas and STIC are multifocal lesions.

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Studies have suggested serous tubal intraepithelial carcinoma (STIC) of the fallopian tube to be a putative precursor to ovarian and peritoneal serous carcinoma. It has been recommended that resected fallopian tube specimens should be rigorously examined for STIC, especially in women at high risk of serous carcinoma, such as those with BRCA mutations or with a strong family history. The SEE-FIM protocol allows for the greatest surface area of the tube to be histologically assessed. There have been suggestions that multiple deeper sections should be examined if the initial hematoxylin and eosin (H&E) sections are negative; however, whether this identifies more cases of STIC has not rigorously examined. We examined deeper sections from 56 cases of pelvic carcinoma in which the initial H&E sections of the fallopian tubes were negative for STIC. All initial and deeper sections underwent consensus review by panel of experts in gynecologic pathology. These cases are part of a larger study in which we had examined 300 consecutive bilateral salpingectomies using the SEE-FIM protocol and a single-H&E section per block and had identified 68 cases of pelvic serous carcinoma, of which 12 were associated with STIC. We calculated the sensitivity of a single-H&E section to detect STIC, as compared with examination of multiple deeper sections, and reevaluated the clinicopathologic data of the parent study in light of the additional cases of STIC. In the 56 cases initially negative for STIC, 4 cases of STIC were identified after examination of multiple deeper sections of the fallopian tubes. The single-H&E section SEE-FIM approach therefore detected only 75% (95% confidence interval, 51%-90%) of STIC that was present. Three of these new cases were associated with primary ovarian serous carcinoma and 1 with primary peritoneal serous carcinoma. All 3 new cases associated with ovarian carcinoma were noted in women without neoadjuvant chemotherapy. In considering the data from the parent study, we calculated a statistically significant lower incidence of STIC in women with ovarian serous carcinoma who received neoadjuvant chemotherapy as compared with those who did not (P=0.042). Our study demonstrated that additional cases of STIC can be detected if deeper sections are examined. These additional cases also highlighted a statistically significant difference in the incidence of STIC associated with ovarian serous carcinoma who received neoadjuvant chemotherapy relative to those who did not. Consideration to this should be given in future studies of the prevalence of STIC and to routine examination of salpingectomy specimens from women at high risk for pelvic serous carcinoma.