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The Origin of Ovarian Carcinomas: A Unifying Hypothesis

Auersperg, Nelly M.D., Ph.D.

International Journal of Gynecological Pathology: January 2011 - Volume 30 - Issue 1 - p 12–21
doi: 10.1097/PGP.0b013e3181f45f3e
PATHOLOGY OF THE UPPER GENITAL TRACT: ORIGINAL ARTICLES
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It is currently a controversial issue whether epithelial ovarian cancers arise in the ovarian surface epithelium (OSE) or the fimbrial epithelium of the oviduct. The hypothesis presented here aims to reconcile these 2 views and provides a possible explanation for 2 questions arising: first, why tumors originating in the fimbriae and OSE, which are parts of different organs, express common features; second, why these epithelia are prone to neoplastic transformation whereas the remaining oviduct and the extraovarian mesothelium are not. We hypothesize that these questions relate to the common origin of the OSE and fimbriae in that region of the embryonic coelomic epithelium, which will eventually link the extraovarian mesothelium to the epithelium of the oviductal ampulla. OSE and fimbriae become separated during embryonic development but, like other transitional, interepithelial junctions in adults, this region might remain incompletely committed and thus prone to neoplastic progression. To define differentiation at the OSE-tubal junction, salpingo-oophorectomy specimens were stained immunohistochemically for mesenchymal differentiation markers of OSE and for epithelial markers and Pax8, characterizing oviductal fimbriae and ampullae. OSE and ampullae were distinctly different, but there was no sharp boundary between OSE and fimbriae. Rather, both mesenchymal and epithelial markers overlapped, and Pax8 and fimbrial epithelial markers diminished distally, near the OSE. The results support the hypothesis that the OSE and fimbriae are parts of a transitional epithelium of common origin rather than 2 independent sources of ovarian cancer, and suggest that their immature, incompletely determined phenotype contributes to their propensity to neoplastic transformation.

Department of Obstetrics and Gynecology, University of British Columbia, and the Child and Family Research Institute, Vancouver, British Columbia, Canada

Supported by a grant to Nelly Auersperg from the National Cancer Institute of Canada.

Address correspondence and reprint requests to Nelly Auersperg, MD, PhD, Department of Obstetrics and Gynecology, University of British Columbia, 2H30-4490 Oak Street, British Columbia Women's Hospital, Vancouver, British Columbia, Canada V6H 3V5. e-mail: auersper@interchange.ubc.ca

©2011International Society of Gynecological Pathologists