Risk of Malignancy in Complex Multiloculated Ovarian Cysts in Postmenopausal Women
A complex multiloculated clear septated ovarian cyst with multiple thin septations in a postmenopausal woman is likely benign if it has remained stable for one year and CA125 is normal. 1
Risk Assessment Based on Imaging Features
- According to the O-RADS US risk stratification system, septated cysts without solid components or papillary projections are classified as low risk for malignancy 2, 1
- The presence of thin septations (<3 mm) is considered a benign feature with a malignancy risk <0.4% 2
- Multilocular cysts <10 cm with smooth inner walls and low color score (1-3) are categorized as O-RADS 3, indicating a low risk of malignancy (1% to <10%) 2
- Stability of an ovarian cyst for one year without growth is a reassuring feature that strongly suggests benign etiology 1
Significance of Normal CA125 Levels
- Normal CA125 values in postmenopausal women have a specificity of approximately 98.5% for ruling out ovarian cancer 1
- All patients with serum CA125 levels <35 IU/ml in one study had benign histopathology regardless of tumor size or ultrasonic features 3
- The combination of normal CA125 and absence of concerning ultrasound features provides high negative predictive value for malignancy 2
Evidence Supporting Benign Nature
- In a study of 226 postmenopausal women with unilocular ovarian cysts followed for 5 years, 76.1% showed no change in cyst diameter or CA125 levels 4
- Another study of 619 postmenopausal women with simple ovarian cysts found that 43.91% of cysts persisted unchanged over the follow-up period, with only one patient developing ovarian cancer three years later 5
- In a prospective study of 30 simple adnexal cysts in postmenopausal women, no malignancies were found among those who underwent surgery 6
Management Considerations
- For postmenopausal women with septated cysts that have remained stable for one year with normal CA125, continued surveillance rather than immediate surgical intervention is appropriate 2, 1
- According to O-RADS management recommendations, multilocular cysts without solid components or concerning features should be managed by a gynecologist rather than requiring gynecologic oncology consultation 2
- Color or power Doppler should be included in ultrasound examinations to differentiate true solid components from debris and to assess vascularity patterns 2
Important Caveats and Pitfalls
- Even with reassuring features, continued surveillance is recommended as some borderline or low-grade malignant lesions may have normal CA125 levels 1
- Progressive elevation of CA125 over time, even within normal range, should prompt further evaluation 1
- The presence of solid components, papillary projections, irregular walls, or high color score would significantly increase the risk of malignancy and require different management 2
- CT is usually not indicated for characterization of adnexal masses without acute symptoms due to its poor soft-tissue discrimination in the adnexal region 2
Conclusion
The combination of stability over one year, normal CA125, and absence of concerning ultrasound features (solid components, papillary projections, irregular walls) strongly suggests a benign etiology for this complex multiloculated clear septated ovarian cyst with multiple thin septations in a postmenopausal woman 2, 1, 3.