Does Presence of Thin Septations Increase Malignancy Risk in Postmenopausal Women?
No, a single thin septation less than 3 mm does not increase malignancy risk and is considered benign in both premenopausal and postmenopausal women. 1
Risk Stratification Based on Septation Characteristics
Single thin septations (<3 mm) are classified as benign features and do not warrant surgical intervention or aggressive management. 1 The ACR Appropriateness Criteria explicitly states that a single thin septation <3 mm is considered benign, with malignancy risk remaining extremely low (<0.4%). 1
Multiple Septations Without Other Features
Multiple septations without papillary projections or solid components are unlikely to be malignant. 1 These cysts fall into the O-RADS 3 category (low risk, 1-10% malignancy) when they are multilocular smooth cysts with low color score (1-3) and measure <10 cm. 1, 2
When Septations Become Concerning
The presence of septations increases malignancy risk only when accompanied by:
- Septal irregularity or thickening ≥3 mm in height, which elevates the lesion to O-RADS 4 (intermediate risk, 10-50% malignancy). 1, 2
- Papillary projections arising from septations (≥3 mm height protruding into cyst cavity), particularly when there are ≥4 such projections, which indicates O-RADS 5 (high risk, ≥50% malignancy). 1, 2
- High vascularity on color Doppler (color score 4) within the septations or associated solid components, which suggests O-RADS 5. 1, 2
Management Algorithm for Septated Cysts in Postmenopausal Women
For Thin Smooth Septations (<3 mm):
- Unilocular or paucilocular cysts <10 cm: No follow-up required if all other features are benign. 2
- Multilocular cysts ≥10 cm: Follow-up ultrasound in 8-12 weeks, then referral to gynecologist if persistent or enlarging. 1, 2
For Irregular or Thick Septations (≥3 mm):
- Immediate referral to gynecologist for cysts with septal irregularity, as these are O-RADS 4 lesions. 1, 2
- Gynecologic oncology consultation if high color score (4) is present, indicating O-RADS 5. 1, 2
Evidence Supporting Conservative Management
Multiple studies demonstrate that simple and minimally septated cysts in postmenopausal women have extremely low malignancy rates:
- Zero malignancies were found in 28 surgical specimens of unilocular postmenopausal cysts ≤5 cm. 3
- No malignancy or borderline histology was observed in 236 cysts (including 54 with isolated septa) in postmenopausal women, even when cysts were >5 cm. 4
- Only 1 malignancy (0.16%) developed among 619 postmenopausal women with simple cysts during extended follow-up, and this occurred 3 years after the last surveillance ultrasound. 5
Critical Pitfalls to Avoid
Do not confuse thin septations with papillary projections. Septations are thin walls dividing cyst compartments, while papillary projections are solid components ≥3 mm protruding into the cyst cavity from the wall or septation. 1, 2 The latter significantly increases malignancy risk.
Do not operate on multilocular cysts with thin smooth septations alone. The presence of thin septations without other concerning features (irregular walls, solid components, high vascularity) does not justify surgery. 1, 4
Ensure complete color Doppler evaluation of all septations to exclude vascular solid components that may be mistaken for simple septations on grayscale imaging. 1, 2
Recognize that size matters more than septations. Cysts ≥10 cm have substantially higher cancer risk regardless of septation presence and warrant closer surveillance or gynecology referral. 1, 2