Endometriosis-associated epithelial ovarian cancer: Primary synchronous different cellular type on each ovary

Objective: Endometriosis-associated epithelial ovarian cancer (EOC) is a specific category of EOC, containing either endometrioid or clear cell carcinoma subtype. The characteristic of endometriosis-associated EOC includes an early stage at the diagnosis, presence of single histology type, and better prognosis. The synchronous two subtypes of endometriosis-associated EOC and presentation of far-advanced stage status at the initial diagnosis is rarely reported. Case report: We reported a 60-year-old postmenopausal woman with FIGO IA endometriosis-associated endometrioid carcinoma at right ovary and FIGO IVA endometriosis-associated clear cell carcinoma at left ovary, right tube, omentum, lymph node and cytology of pleural effusion and ascites treated with optimal debulking surgery and dose-intensity taxane/platinum based chemotherapy. Conclusion: This case report confirms the long-term concept that clear cell carcinoma has much more aggressive behavior than endometrioid cell carcinoma does, regardless of association of endometriosis or not.