The Silent Malignancy: Clear Cell Ovarian Cancer Masquerading as a Benign Adnexal Mass The Silent Malignancy: Clear Cell Ovarian Cancer Masquerading as a Benign Adnexal Mass GEORGE ELIOT HOSPITAL NHS TRUST, O&G, NUNEATON, UNITED KINGDOM . EP 0819 1 GEORGE ELIOT HOSPITAL NHS TRUST, O&G, NUNEATON, UNITED KINGDOM . EP 0819 1 Clear cell ovarian carcinoma is a rare epithelial subtype often presenting deceptively as benign on imaging and tumour markers. Misclassification can delay treatment, risking disease upstaging. BACKGROUND The case underscores the subtlety of clear cell carcinoma, often lacking solid components or raised CA125. Conservative management risks intraoperative spillage and upstaging. Early surgical intervention with intact specimen retrieval mitigated this risk. DICUSSION Clear cell ovarian cancer is a diagnostic challenge. A high index of suspicion and appropriate surgical planning are essential for optimal outcomes. MDT involvement and thorough histopathology are crucial in identifying rare malignancies. CONCLUSION 1.Kim JY et al. Clear cell carcinoma of the ovary: A review. Gynecol Oncol. 2011;122(3):470–8. 2.RCOG Green-top Guideline No. 62: Management of Suspected Ovarian Masses. 3.Timmerman D et al. Simple ultrasound-based rules for the diagnosis of ovarian cancer. BMJ. 2010;341:c6839. REFERENCES A 56-year-old postmenopausal woman presented with left iliac fossa pain. Imaging revealed bilateral 4–5 cm adnexal masses. IOTA ultrasound scoring and MRI ORADS classified them as benign (ORADS 2), with normal CA125 levels. CASE SERIES SUMMARY OTA/ORADS Scoring Summary Initially opting for cystectomy, she later consented to laparoscopic BSO. Surgery was uneventful with intact specimen retrieval. Unexpectedly, histopathology confirmed clear cell carcinoma confined to the ovary. Highlighting limitations of imaging-based risk assessment in certain malignancies. The features to the left led to an initial benign classification under both IOTA and ORADS scoring systems. MDT referral led to staging investigations and oncological follow-up. Clear cell carcinoma can appear benign on imaging and tumour markers. Postmenopausal adnexal masses warrant a cautious approach regardless of ORADS score. Surgical planning should consider oncological principles even for presumed benign masses. LEARNING POINTS AUTHOURS: IFTIKHAR SOHAIL, HIRSI-FARAH SUAD 1 1 AUTHOURS: IFTIKHAR SOHAIL, HIRSI-FARAH SUAD 1