MRI characteristics of intraductal papilloma

Background: Intraductal papilloma (IDP) is the most common pathological finding in women with pathological nipple discharge. Magnetic resonance imaging (MRI) has shown potential for characterizing breast tumors; however, MRI findings of IDPs are inconclusive, and certain diagnostic standards are lacking.

Purpose: To characterize the MRI features of IDP from a relatively large cohort.

Material and methods: We retrospectively reviewed from 358 women with IDPs that were confirmed by histopathology. The clinical and imaging findings in 70 patients who underwent preoperative MRI were analyzed. MRI analyses included morphology and dynamic contrast-enhanced MRI.

Results: In 70 patients, 77 IDPs were detected on MRI, which revealed the following three patterns: small luminal mass papillomas; tumor-like papillomas; and MRI-occult papillomas. Fourteen IDPs involved small, oval, smooth, and contrast-enhanced masses at the posterior end of the enlarged duct corresponding to small luminal mass papillomas. Seven IDPs had large diameters along the direction of the breast duct, indicating the typical MRI findings for IDP. Of 47 tumor-like papillomas, 16 cases showed large diameters along the direction of the breast duct and close to the nipple (within 4 cm), seven cases resembled invasive breast cancer on MRI, and the remaining 24 were (24/47) undistinguishable from other benign breast diseases. Sixteen IDPs were MRI-occult papillomas that could not be distinguished from the surrounding benign disease by either contrast-enhanced MRI or fat-suppressed T2-weighted MRI.

Conclusion: Small luminal mass papillomas or tumor-like papillomas with the largest diameters along the direction of the breast duct and close to the nipple (within 4 cm) might be the typical MRI findings for IDPs.