Magnetic resonance imaging of intraductal papilloma of the breast.

To describe the appearance of isolated intraductal papilloma on contrast-enhanced water-specific, high spatial-resolution and rapid dynamic breast MRI, a retrospective review of unilateral breast images of 15 pathologically proven papilloma was performed. MRI revealed three patterns: Four papillomas were small, smooth, enhancing masses at the posterior end of an enlarged duct, corresponding to the "small lumenal mass" appearance of papilloma known from galactography. MRI detected two of these "small lumenal mass" papillomas in patients with abnormal nipple discharge even when galactography was unsuccessful. Seven papillomas were irregular enhancing masses detected in patients without nipple discharge. None of these papillomas had specifically benign findings. All seven demonstrated rapid enhancement and three showed rim enhancement or spiculation. These "tumor-like" papillomas mimicked invasive breast cancer on MRI. Four papillomas were occult on MRI, not revealed by either contrast-enhanced MRI or fat-suppressed T(2)-weighted MRI. Intraductal papillomas present with a variable appearance on MRI ranging from occult to "small lumenal mass" papillomas to irregular rapidly enhancing lesions that cannot be distinguished from invasive cancers.