Diagnostic and molecular genetic pathology of serous borderline tumours of the ovary

Abstract Serous borderline tumours of the ovary (SBOTs) are distinct tumour entities which have to be distinguished from benign serous adenomas and frankly malignant serous carcinomas. Morphological examination has to include a careful analysis of associated extraovarian lesions, which may present as Mullerian inclusion cysts, endosalpingiosis, non-invasive or invasive implants. The type and extent of extraovarian disease manifestation is the most important prognostic factor of SBOT. Molecular pathology has revealed activation of the RAS–BRAF pathway as the most frequent genetic aberration in SBOT and has furthermore helped to elucidate the pathogenesis of some extraovarian lesions associated with these tumours.