Polypoid endometriosis is a rare presentation of endometriosis which may mimic various pelvic malignancies. In this study, we aim to explain a rare case and review the specific features in multiple imaging modalities for differentiating benign from malignant lesions.

The patient was a 27-year-old woman presenting with highly vascular multiloculated solid cystic pelvic mass, separate from ovaries and uterus with high T1 signal in cystic components. There were conflicting appearances ranging from sarcoma to endometriosis related malignancy or benign endometriosis related pathology in ultrasound and MRI. After surgical excision, polypoid endometriosis was confirmed in pathology.

The radiologists have to be familiar with imaging characteristics of polypoid endometriosis in different imaging evaluations. Imaging features such as dark T2 signal intensity, lack of diffusion restriction, and smooth border help them to make an accurate diagnosis and appropriate management.