Polypoid endometriosis mimicking aggressive pelvic malignancy on MRI in a premenopausal woman: A case report

Polypoid endometriosis is a rare benign variant of endometriosis characterized by exuberant mass-forming endometrial tissue that can closely mimic aggressive pelvic malignancy on imaging. Although it most commonly affects peri- or postmenopausal women and is frequently associated with estrogen exposure or tamoxifen therapy, recent literature demonstrates that it can also occur in younger, premenopausal, and pregnant patients without identifiable hormonal risk factors. This report describes a case of polypoid endometriosis identified on pelvic imaging in a premenopausal woman, manifesting as a large heterogeneous mass with avid enhancement and suspicious infiltrative features, raising strong concern for pelvic cancer. Extensive diagnostic evaluation was pursued, and histopathologic examination ultimately confirmed polypoid endometriosis. This case highlights the expanding clinical spectrum of this uncommon entity and underscores the importance of recognizing its imaging features to avoid misdiagnosis and unnecessary aggressive surgical management. • Polypoid endometriosis can mimic aggressive pelvic malignancy on MRI. • The report describes a rare case in a premenopausal patient without estrogen exposure. • MRI showed a heterogeneous T2 signal and avid enhancement, suggesting a malignancy. • Extensive diagnostic evaluation and histopathologic examination ultimately confirmed polypoid endometriosis. • Awareness may prevent unnecessary radical oncologic surgery.