Breast cancer treatment has greatly evolved from radical mastectomy to more cosmetically acceptable and less-debilitating surgeries. Nipple-sparing mastectomy is increasingly done for both cancer treatment and risk reduction. The frequency of terminal duct lobular units (TDLUs) and occult neoplastic epithelial proliferation in grossly/clinically unremarkable nipples (GUNs) is not well investigated.
To describe frequency of TDLUs and occult and overt neoplastic nipple involvement.
Nipples from 105 consecutive specimens (90 therapeutic, 15 prophylactic) were studied. Sixty-five nipples were entirely submitted to evaluate frequency of TDLUs; the rest had 1 vertical section submitted.
Terminal duct lobular unit was seen in 17 GUNs (26%). Six had TDLU in the base, 6 had it in the papilla, and 5 in both. Four GUNs showed lobular carcinoma in situ (1), Paget disease (1), and pagetoid extension of underlying malignancy (2). Grossly/clinically abnormal nipples had Paget disease (2), lymphovascular invasion (2), invasive carcinoma (4), and pagetoid extension (5). Involved nipples were closer to tumor (mean, 1.1 versus 3.2 cm, P < .001), had larger underlying tumors (mean, 4.3 versus 2.6 cm, P = .03) and of higher grade (P = .04), and more often had lymph node metastases (91% versus 44%, P = .007). No pathologic abnormalities were found in prophylactic mastectomy nipples.
Terminal duct lobular units were seen in 26% of nipples. They were frequently seen in the nipple papilla. Occult neoplastic epithelial proliferation was seen in 5% of grossly/clinically unremarkable therapeutic mastectomy nipples. Pagetoid extension was the dominant spread of underlying malignancy. Overall, the nipple was more often involved by larger and higher-grade tumors located closer to the nipple. All prophylactic mastectomies had unremarkable nipples. These findings should be considered while selecting patients for nipple-sparing mastectomy.