Diagnostic Accuracy of Nonmass Enhancement at Breast MRI in Predicting Tumor Involvement of the Nipple: A Prospective Study in a Single Institution.

Background Although nonmass enhancement (NME) extension to the nipple at preoperative MRI frequently leads to sacrifice of the nipple-areolar complex (NAC), its correlation with pathologically confirmed NAC involvement is unclear. Purpose To evaluate the diagnostic accuracy of using NME extension to the subareolar region at breast MRI to predict pathologic nipple involvement and the eligibility for nipple-sparing mastectomy. Materials and Methods From November 2017 to November 2019, the authors prospectively enrolled participants with breast cancer and NME within 2 cm of the nipple at breast MRI who underwent surgery that included removal of the NAC. The authors evaluated NME extensions that were ipsilateral and contiguous with the biopsy-proven tumor lesions on images acquired during the early contrast phases. Pathologic nipple involvement and the distance from the nipple to the nearest cancer cell were evaluated by using serial vertical sectioning of the area extending from the entire NAC to the tumor. The primary end point was the positive predictive value (PPV) of NME, which was calculated as follows: (number with pathologic nipple invasion and NME extension to the nipple at breast MRI/number with NME extension to the nipple at breast MRI) × 100. Results Of 64 women (mean age, 52 years ± 9.8 [standard deviation]), 49 (77%) had NME extension to the nipple at breast MRI. The PPV of NME extension to the nipple was 86% (42 of 49 women; 95% CI: 73, 94). Among the 15 participants without NME extension to the nipple, only one (7%) had pathologic nipple involvement. The diagnostic accuracy of using NME extension to the nipple was 88% (56 of 64 women; 95% CI: 77, 95). The radiologic distance correlated well with the pathologic distance (Spearman correlation coefficient = 0.71, P = .003). Conclusion Nonmass enhancement extension to the nipple base at preoperative MRI has a high positive predictive value for identifying tumor involvement of the nipple, a contraindication to nipple-sparing mastectomy. © RSNA, 2021 Online supplemental material is available for this article.

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.