Abstract

Background: The cumulative evidences, both clinicopathological and molecular in the past decade that high-grade serous ovarian carcinoma results from clonal expansion of secretory cells of the distal fallopian tube, rather than ovary. We explored this relationship based on morphological and immunohistochemical studies of a lesion designated “serous tubal intraepithelial carcinoma” (STIC), which closely resembles high-grade ovarian serous carcinoma. This tubal lesion is the plausible origin for pelvic serous carcinomas.
Objective: To study the association between ovarian serous carcinoma and STIC. Material and Methods: We studied 44 consecutive cases of epithelial ovarian carcinomas from February 2013 to January 2015, including 29 serous, 12 mucinous, and 3 endometrioid. Complete examination of fallopian tubes from each case was done according to serial sectioning and extensive examination of fimbria (SEEFIM) protocol. All the cases were grouped into high-grade serous (27 cases), and non-high-grade serous (17 cases) groups. Immunostaining for p53 and MIB-1 was done on the sections from ovary and fallopian tube.
Results: STIC lesion was identified in fallopian tubes from 10 cases of high-grade serous group (37%) while no STIC was identified in non-high-grade serous group. Eighty percent% of the STIC identified were confined to the fimbria of fallopian tube. Results from both groups were compared using chi square test. A statistically significant association was found between high-grade serous carcinoma group and STIC (P = 0.013). Conclusion: STIC coexists with a significant number of high-grade serous carcinoma cases and further studies are needed to elucidate etiological significance of STIC in high-grade serous carcinoma.