Ovarian borderline tumors, a subtype of neoplasm with controversial behavior. Role of Ki67 as a prognostic factor.

Introduction: Ovarian borderline tumors (OBT) are tumors with an intermediate grade of malignancy whose diagnosis is purely based on morphological criteria. They usually occur in young women (under 40 years) and are characterized by a cellular proliferation with slight nuclear atypia and lacking stromal invasion with a destructive pattern. Aim of this study was to explore the immunohistochemical expression of Ki67 proliferative index in OBT and to correlate it with known clinicopathologic prognostic factors in patients older than 40 years.
Material and Methods: Twenty cases of OBTdiagnosed in the period ranging from 2016 to 2018 were retrieved. Each specimen was taken from hysterectomy or adnexectomy surgery. Immunohistochemical studies were performed on the most representative sample of the tumor. Positive signal was nuclear and it was evaluated by three independent pathologists.
Results: Ki67 Labelling Index (L.I.) value ranged from 2% to 40%, with an average value of 14% and a median of 10%. Higher Ki67 L.I. was observed in patients older than 40 years (pvalue = 0.0194) and in those with tumors with a maximum diameter ≥ 10 cm (pvalue = 0.0547). Furthermore, a direct correlation was evident between tumor size value and Ki67 L.I. (p value<0.0001, r = 0.7745). Hitherto no known prognostic factor correlated with high Ki67 L.I.
Conclusions: Overall, OBT are tumors with greater risk of evolution at a more advanced age and when they are greater in size. The assessment of Ki67 could be a valid support in the diagnosis of a more aggressive tumor. Further studies are needed to assess possible correlation with data concerning recurrences rate, that in our cases were not available.
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