Terminal Duct Lobular Units are Scarce in the Nipple: Implications for Prophylactic Nipple-Sparing Mastectomy

Background The use of nipple-sparing mastectomy (NSM) for both breast cancer treatment and risk reduction is increasing. There is no randomized data comparing nipple-sparing mastectomy with standard mastectomy techniques. There is evidence to suggest that ductal and lobular breast cancer arises in the terminal duct/lobular unit (TDLU). This study was undertaken to determine whether TDLUs exist in the nipple and if so, to what extent. Methods At the time of mastectomy the nipple papilla was excised and submitted for separate pathological examination. The presence or absence of TDLUs was noted. Results Thirty-two nipples were studied in 22 patients. There were no TDLUs in 29 specimens. Three of 32 nipple specimens were found to contain TDLUs. The three nipples contain one, two, and three TDLUs respectively. All TDLUs were found at the base of the nipple, with none located near the tip. Conclusions The infrequent occurrence of TDLUs in the nipple papilla supports the use of NSM for risk reduction surgery, including for those women with BRCA1/2 mutations.