Significance of Non-Mass Enhancement in the Subareolar Region on Preoperative Breast Magnetic Resonance Imaging for Nipple-Sparing Mastectomy

Purpose: The eligibility for nipple-sparing mastectomy (NSM) regarding subareolar non-mass enhancement (NME) on breast magnetic resonance imaging (MRI) was not clear. This study aimed to evaluate the eligibility for NSM according to the NME-to-nipple distance on preoperative breast MRI. Methods: We identified patients with breast cancer who underwent mastectomy with NME suspected of malignancy in the subareolar region on preoperative breast MRI. The incidence of nipple invasion was pathologically evaluated according to the NME-to-nipple distance on breast MRI, and the clinicopathologic factors related to pathologic nipple invasion were analyzed. Results: Of 137 patients, 55 (40.1%) had NME extension to the nipple, 53 (38.7%) had radiologic distance less than 2 cm, and 29 (21.2%) had radiologic distance of 2 cm or more. The rate of pathologic nipple invasion was 52.7% (29 of 55) in patients with NME extension to nipple, 7.5% (4 of 53) in patients with NME-to-nipple distance less than 2 cm, and 3.4% (1 of 29) in patients with NME-to-nipple distance of 2 cm or more (P < .001). NME extension to the nipple was an independent risk factor for pathologic nipple invasion (odds ratio 21.702; 95% confidence interval, 2.613–180.225; P = .004). The survival outcome was not different between NSM and conventional total mastectomy/skin-sparing mastectomy in patients with radiologic distance less than 2 cm, but without NME extension to the nipple. Conclusions: NSM is an acceptable procedure in patients with breast cancer with a low incidence of pathologic nipple invasion when there is no evidence of NME extension to the nipple on preoperative breast MRI.