Adenoma of the nipple (nipple adenoma) is a rare breast tumor that can show various histologic features. We present magnetic resonance (MR) and other imaging findings of a case of nipple adenoma and correlate them with detailed histologic features of the tumor. The lesion showed early strong enhancement with rim enhancement on dynamic contrast-enhanced MR images, and internal portions of the lesion showed washout on delayed MR images. Histologically, the tumor showed expansive growth with surrounding dense collagenous tissue and large vessels. Internal portions of the lesion showed a relatively low degree of fibrosis compared with that of the surrounding area, and tiny vessels were observed. These features were clearly reflected in the MR findings.