Solitary intraductal papillomas of the breast: MRI features and differentiation from small invasive ductal carcinomas

OBJECTIVE. Intraductal papilloma of the breast can resemble invasive ductal carcinoma (IDC). The purpose of this study was to characterize MRI features of solitary intraductal papillomas and identify features that differentiate intraductal papillomas from small IDCs. MATERIALS AND METHODS. Forty-four intraductal papillomas and 49 small (diameter ≤ 2.0 cm) IDCs confirmed by histopathology were included. Analysis of MR findings included morphology, signal intensity preenhancement, time-signal intensity curve (TIC), enhancement degree, and evolution of enhancement pattern on dynamic contrast-enhanced MRI (DCE-MRI), and diffusion-weighted imaging. The chi-square test and independent-samples Student t test were performed. RESULTS. Of 44 intraductal papillomas, 27 (61.4%) were round or oval and 17 (38.6%) were irregular in shape, whereas 38 of 49 (77.6%) IDCs showed irregular or lobular shape (p < 0.001). Smooth margins were seen in 43.2% (19/44) of the intraductal papillomas and 8.2% (4/49) of the IDCs. Most intraductal papillomas and IDCs showed slightly higher signal intensity on T2-weighted images. On DCE-MRI, 68.2% (30/44) of intraductal papillomas and 12.2% (6/49) of IDCs showed an early homogeneous or heterogeneous to delayed rimlike enhancement pattern (p = 0.000). The difference in early-phase enhancement rates between intraductal papillomas (155.41% ± 19.15%) and IDCs (176.40% ± 35.61%) was significant (p = 0.001). Differences in TIC and apparent diffusion coefficient values between the two groups were not significant. CONCLUSION. A low early-phase enhancement rate and evolution of the DCE-MRI enhancement pattern from homogeneous or heterogeneous enhancement to rim enhancement is more likely to suggest intraductal papilloma than IDC.