Up to 15% of ovarian cancers are etiologically linked with hereditary susceptibility. Within this group, germline mutations in mismatch repair (MMR) genes, known otherwise as Lynch syndrome (LS), account for the majority of cases that are not associated with mutations in BRCA1 or BRCA2. Clinical schemas specific for gynecologic cancers have been developed to identify patients with LS; however, many of the recommendations are poorly defined. Few case series of germline-confirmed LS-associated ovarian cancers have been reported, limited by small sample size and often lacking central pathology review. Much insight has been gained from studies of unselected cohorts, using immunohistochemical assessment of MMR protein expression or microsatellite instability analysis. In spite of contradictory results, likely reflective of differences in study design, sample size and methodology, a recurring observation is the overrepresentation of “endometriosis-associated tumors,” namely, endometrioid and clear cell subtypes, in the group of ovarian tumors with MMR deficiency. In this review, we summarize the clinical and histomorphologic features of LS-associated/MMR-deficient ovarian epithelial cancers and recommend that reflex testing be performed on the basis of tumor subtype.
*Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto
§Department of Pathology, Toronto General Hospital, University Health Network, Toronto, ON
†Department of Pathology and Laboratory Medicine, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
‡Department of Pathology and Laboratory Medicine, Hospital of the University of Pennsylvania, Philadelphia, PA
The authors have no funding or conflicts of interest to disclose.
Reprints: Blaise A. Clarke, MBBCh, FRCPC, Department of Pathology, Toronto General Hospital, University Health Network, 200 Elizabeth Street, Rm 11E404, Toronto, ON, Canada M5G 2C4 (e-mail: firstname.lastname@example.org).