Objective: The purpose of this study is to determine the diagnostic utility of MRI after negative or inconclusive mammography for the evaluation of pathologic nipple discharge.
Materials and methods: We conducted a retrospective review of breast MRI examinations from January 1, 2006, through December 31, 2015, that were performed after negative or inconclusive mammography for the evaluation of nipple discharge. Clinical notes, imaging findings, and pathology outcomes were reviewed.
Results: One hundred eighteen women (mean age, 49 years; range, 23-82 years) underwent MRI for evaluation of nipple discharge, 105 (89.0%) of whom had surgical excision or at least 2-year imaging follow-up. A total of six patients (6/105; 5.7%) were diagnosed with malignancy (ductal carcinoma in situ [DCIS] or invasive malignancy). Of 27 patients with positive MRI findings (final assessment of BI-RADS category 4), three (11.1%) were diagnosed with malignancy: DCIS grade 2-3, DCIS with focus of microinvasive ductal carcinoma, and invasive papillary carcinoma. An additional three patients (without suspicious findings at MRI) were diagnosed with malignancy at surgical excision, all of which were grade 1 DCIS. For patients with negative MRI findings (BI-RADS category 1, 2, or 3), the negative predictive value of MRI for malignancy was 96.2% (75/78).
Conclusion: In women with nipple discharge and negative or inconclusive mammography findings, the risk of malignancy is low, at 5.7%. With negative MRI findings (BI-RADS category 1, 2, or 3), the risk of malignancy is less than 4%. Surveillance rather than surgical excision may be a reasonable option for patients without suspicious findings at MRI.
Keywords: MRI; breast; nipple discharge.