Pretreatment evaluation of axillary lymph nodes and marking of biopsied nodes in patients with newly diagnosed breast cancer is becoming routine practice. Tagging of biopsied axillary lymph nodes with metal markers, similar to what is done for suspicious breast lesions, is being adopted in clinical practice. The need to mark a positive axillary lymph node becomes especially relevant in cases where neoadjuvant chemotherapy (NACT) is anticipated so that these nodes may be identified at the time of surgery. Measures that improve both the accuracy of nodal evaluation after NACT and the ability to assess treatment response are desirable in order to tailor therapies for breast cancer treatment. The investigators sought to test tattooing of biopsied axillary lymph nodes with a sterile black carbon suspension.