Postmenopausal Endometriosis: Clinical Insights and Imaging Considerations

Endometriosis is a chronic systemic condition characterized by the presence of ectopic endometrial-like tissue outside of the uterus. It occurs most often in reproductive-aged patients and less frequently in postmenopausal women. In postmenopausal patients, endometriosis is more common in those undergoing hormone replacement therapy or taking tamoxifen. The risk of malignant transformation of endometriosis is higher in this older population, especially in those undergoing estrogen-only hormone replacement therapy. Many theories on the postmenopausal pathogenesis of endometriosis have been proposed, ranging from reactivation of premenopausal disease to de novo manifestation. Compared with premenopausal disease, postmenopausal endometriosis is typically less active and extensive, with fewer hemorrhagic components. Patients may be symptomatic, with chronic pelvic pain, or may receive the diagnosis after imaging performed for other indications such as an incidental ovarian lesion. Treatment is typically surgical resection or estrogen-blocking medications. Although the diagnosis requires pathologic confirmation, radiologists play an important role in diagnosing both benign endometriosis and malignant transformation. Pelvic US following a dedicated protocol is an accessible screening tool, with high sensitivity for diagnosis of bowel-invasive disease. MRI has better anatomic resolution and allows simultaneous characterization of adnexal and extrapelvic lesions, thereby providing excellent assessment for malignant transformation.