Introduction/Background Malignant transformation of extra-ovarian endometriosis is a rare and aggressive disease. The purpose of this study is to provide a clinical overview, focusing on risk factors affecting prognosis.

Methodology We performed a Preferred Reporting Items for Systematic Reviews and Meta-Analyses-compliant systematic review based on prior reviews and case reports regarding the phenomenon published in English, from 1954 to 2019. Descriptive data were collected and analyzed.

Results Of 316 patients (mean age was 51.2) included, the common primary clinical presentation was mass and /or abdominal pain (72.3% and 46.2%, respectively).The frequent sites of extra-gonadal involvement are the intestine (26.3%) and the abdominal wall (16.9%). Endometrioid carcinoma was the most prevalent histology (40.1%), followed by clear-cell carcinoma (21.3%). Extensive Surgery was the major part of the therapeutic approach in patients, with/without adjuvant treatment. The median survival time was 132 months since diagnosis. According to our data analysis, patients who younger than 45-years-old presented a trend of survival lower than elder ones (p=0.024). Tumor diameter ≥8 cm showed a tendency toward worse prognosis relative to both overall survival (P=0.0081) and disease free survival(P=0.024).Clear-cell histology has a higher recurrence rate versus endometrioid carcinoma (P=0.0098) and stroma (P=0.0045).

Conclusion Malignant transformation of extra-ovarian endometriosis is a rare entity with poor prognosis. Patiens who are menopause, who have long term history of endometriosis and with growing mass should pay special attention. Large size of tumor and clear-cell histology tends to poor prognosis. Complete tumor resection is the primary treatment, but it remains unclear whether adjuvant chemotherapy is suitable. Further investigation need to be conducted.

Disclosure Nothing to disclose