Criteria for assignment of primary site in extrauterine HGSC
| Criteria | Primary site | Comment |
| STIC present | Fallopian tube | Regardless of presence and size of ovarian and peritoneal disease |
| Invasive mucosal carcinoma in tube, with or without STIC | Fallopian tube | Regardless of presence and size of ovarian and peritoneal disease |
| Fallopian tube partially or entirely incorporated into tubo-ovarian mass | Fallopian tube | Regardless of presence and size of ovarian and peritoneal disease |
| No STIC or invasive mucosal carcinoma in either tube in presence of ovarian mass or microscopic ovarian involvement | Ovary | Both tubes should be clearly visible and fully examined by a standardised SEE-FIM protocol regardless of presence and size of peritoneal disease |
| Both tubes and both ovaries grossly and microscopically normal (when examined entirely) or involved by benign process in presence of peritoneal HGSC | Primary peritoneal HGSC | As recommended in the 2014 WHO classification7, this diagnosis should only be made in specimens removed at primary surgery before any chemotherapy; see below for samples following chemotherapy |
| HGSC diagnosed on small sample, peritoneal/omental biopsy or cytology, OR HGSC examined post-chemotherapy | Tubo-ovarian | Note: this should be supported by clinicopathological findings to exclude mimics, principally uterine serous carcinoma |
HGSC, high-grade serous carcinoma; SEE-FIM, Sectioning and Extensively Examining the FIMbriated End; STIC, serous tubal intraepithelial carcinoma; WHO, World Health Organization.