What is the most common cause of an adnexal mass in a postmenopausal woman?

Most Common Cause of Adnexal Mass in Postmenopausal Women

The most common solid adnexal mass in postmenopausal women is a pedunculated leiomyoma (also called myoma or fibroid), which is present in approximately 20-30% of postmenopausal women. 1

Types of Adnexal Masses in Postmenopausal Women

Cystic Masses

• Simple cysts are common in postmenopausal women, with a frequency of 17-24% 1
• These cysts are typically benign, with US identification of a simple cyst establishing a benign process in 100% of postmenopausal women 1
• The natural history of simple adnexal cysts shows that 53% disappear completely, 28% remain constant in size, and only a small percentage show changes in size over time 1
• Simple cysts are not related to hormonal therapy or time since onset of menopause 1

Solid Masses

• Pedunculated leiomyomas (fibroids) are the most common solid adnexal masses in postmenopausal women 1
• Other solid ovarian masses include:
  • Mature teratomas (dermoids) 1
  • Fibromas and thecomas 1
  • Brenner tumors 1
  • Chronically torsed ovary 1
  • Malignant ovarian tumors (primary and metastatic) 1

Diagnostic Considerations

Imaging Approach

• Transvaginal ultrasound is the essential initial imaging modality for evaluating adnexal masses 1, 2
• Ultrasound can triage the majority of adnexal masses into benign or malignant categories 1
• For indeterminate masses, MRI with intravenous contrast becomes the modality of choice 1
• Color or power Doppler should be included in the ultrasound examination to help differentiate between benign and malignant masses 1

Distinguishing Features

• Pedunculated fibroids can sometimes be mistaken for solid ovarian masses 1
• Careful identification of normal ovaries (which may be displaced by uterine myomas) and blood supply from uterine vessels helps avoid this error 1
• Most malignant ovarian masses can be diagnosed by US or MRI when there are enhancing solid components or enhancing mural nodules or papillary projections 1

Management Considerations

Simple Cysts

• For postmenopausal women, simple cysts <3 cm require no follow-up due to extremely low risk of malignancy 3
• The risk of malignancy in benign-appearing lesions on ultrasound is only 0.3% to 0.4% 3
• The risk of acute complications such as torsion or cyst rupture is similarly low at 0.2% to 0.4% 3

Complex or Suspicious Masses

• Women with complex masses or masses suspicious for malignancy should be referred to a gynecologic oncologist 2
• Laparoscopy is an effective tool for investigation and treatment of suspected adnexal masses in postmenopausal women when expectancy is not advisable 4

Clinical Pitfalls to Avoid

• Mistaking pedunculated fibroids for ovarian masses - always look for normal ovaries and identify the blood supply from uterine vessels 1
• Unnecessary surgical intervention for simple cysts - studies have shown that small (<5 cm), unilocular postmenopausal cysts have a low incidence of malignant disease 5
• Failing to use color Doppler in the evaluation - this is essential for differentiating true solid components from solid-appearing debris within a cyst 1
• Relying solely on CA-125 - this marker performs worse than ultrasound in distinguishing benign from malignant lesions and may be low with borderline and low-grade malignant tumors 1