Mucinous carcinoma of the breast: MRI features of pure and mixed forms with histopathologic correlation.

Objective: The purpose of this study was to describe the MRI features of the pure and mixed forms of mucinous carcinoma of the breast and the histopathologic correlation.

Materials And Methods: Seventeen pure and three mixed mucinous tumors of the breast were examined with T2-weighted MRI and triple-phase dynamic MRI. MR images were reviewed for evaluation of the signal intensity and enhancement patterns of tumors and for correlation with the histopathologic findings.

Results: The presence of very high signal intensity on T2-weighted images was a common feature of pure and mixed mucinous tumors. Fourteen pure tumors and one mixed tumor had very high signal intensity, and three pure and two mixed tumors had very high signal intensity and isointensity on T2-weighted images. The enhancement pattern during the early phase varied with the cellularity of pure tumors and with the distribution of nonmucinous components in mixed tumors. Hypocellular pure mucinous tumors had a typical pattern of gradual enhancement.

Conclusion: Hypercellular pure mucinous tumors exhibit strong early enhancement and may be difficult to differentiate from mixed mucinous tumors. The distinction between the pure and mixed forms of mucinous carcinoma is important because mixed mucinous carcinoma more frequently undergoes lymph node metastasis and has a poorer prognosis than does pure mucinous carcinoma.