Hard and Soft MRI Signs of Nipple-Areolar Complex Involvement in Breast Cancer

Background: Accurate preoperative assessment of nipple-areolar complex (NAC) involvement is essential for determining the feasibility of nipple-sparing surgery in breast cancer. Magnetic resonance imaging (MRI) offers high sensitivity, but interpretation may be confounded by benign mimics of malignancy. Purpose: To identify and evaluate MRI features predictive of pathologically confirmed NAC involvement in breast cancer. Material and Methods: This retrospective study included 78 breast cancer patients with suspected NAC involvement on preoperative MRI performed between 2015 to 2024. All cases had surgical pathology confirmation. MRI findings were assessed for tumor morphology, tumor-to-nipple distance, ductal enhancement, and direct tumor extension. Logistic regression analyses were used to determine the association between imaging features and NAC involvement. Results: Among 58 eligible cases (excluding 20 patients), 31 (53%) had pathologically confirmed NAC involvement. Direct tumor extension and tumor proximity < 10 mm was most frequently associated with positive findings. On multivariate analysis, mass-forming tumors within 10 mm of the nipple demonstrated significantly increased odds of NAC involvement (OR 4.32; P = .0095), particularly when combined with ductal enhancement or hormone receptor positivity. Conclusion: MRI features most predictive of NAC involvement include direct tumor extension and short tumor-to-nipple distance. These “hard signs” support excision of the NAC. In contrast, “soft signs” such as ductal enhancement or ductal dilatation, without direct continuity may warrant further diagnostic workup before ruling out nipple preservation.