Borderline epithelial ovarian tumors: what the radiologist should know.

Ovarian borderline tumors are neoplasms of epithelial origin that are typically present in young patients and tend to have a less aggressive clinical course than malignant tumors. Accurate diagnosis and staging of borderline tumors has important prognostic and management implications (like fertility-sparing procedures) for women of child-bearing age. This article will review the sonographic, CT, and MRI features of borderline epithelial ovarian tumors with histopathologic correlation. Borderline tumors have less soft tissue and thinner walls/septations than malignant tumors. Serous borderline tumors more commonly have papillary projections, which can simulate the appearance of a sea anemone. Mucinous borderline tumors often are larger, multi-cystic, and more commonly unilateral. The borderline mucinous tumors may also present with pseudomyxoma peritonei, which can make it difficult to distinguish from malignant mucinous carcinoma. Ultrasound is usually the first-line modality for imaging these tumors with MRI reserved for further characterizing indeterminate cases. CT is best used to stage tumors for both locoregional and distant metastatic disease. Overall, however, the imaging features overlap with both benign and malignant ovarian tumors. Despite this, it is important for the radiologist to be familiar with the imaging appearances of borderline tumors because they can present in younger patients and may benefit from different clinical/surgical management.