Ovarian fibroma/fibrothecoma: retrospective cohort study shows limited value of risk of malignancy index score

Abstract

Background: Ovarian fibromas/fibrothecomas are uncommon benign tumours of ovary. Due to their solid structure, these benign tumours are sometimes confused with malignant tumours during clinical evaluation.

Aims: To determine the clinico-pathological characteristics of ovarian fibroma/fibrothecoma and analyse the efficiency of risk of malignancy index (RMI) scoring system to distinguish malignancy among these tumours.

Methods: Between November 2001 and February 2012, women with a pathological diagnosis of ovarian fibroma/fibrothecoma were identified. Depending on the menopausal status, serum CA-125 level and ultrasonographic findings, RMI scores were calculated for each of the patients.

Results: During the study period, 43 ovarian fibroma/fibrothecoma (4.7%) were detected among 912 adnexal masses operated. The mean age of the women was 52.2 (range, 21-80 years). Upon calculating RMI scores, 33 women (76.7%) were classified as low risk and 10 women (23.3%) as high risk for malignancy. Sensitivity, specificity, positive predictive value and negative predictive value of the RMI scoring for identification of malignant lesions preoperatively were found as 0%, 76%, 0% and 97%, respectively. Final pathological diagnosis was ovarian fibroma in 13 (30%) women, fibrothecoma in 29 (67%) and fibrosarcoma in one woman (2%).

Conclusion: There are no specific markers for accurate preoperative diagnosis of ovarian fibroma/fibrothecoma. Moreover, according to our results, RMI scoring system does not aid clinicians in this issue either, with a high false-positive rate and very low sensitivity. Further studies with higher number of cases are needed to state clearly the role of RMI scores in preoperative discrimination of malignancy.