• This is a phase II, prospective, single-center, non-randomized, non-controlled study.
• Sentinel lymph node biopsy (SNB) is a standard staging procedure in early breast cancer. The potentially increasing false negative rate of SNB was concerned if the sonographic abnormal node was not excised. The aim of this study was to evaluate the accuracy of SNB in breast cancer with sonographic abnormal axillary lymph nodes.

Inclusion Criteria:

• histologically confirmsed primary breast cancer by core neelde biopsy or excisional biospy
• abnormal axillary lymph node was found by ultrasound examination before SLNB (abnormal nodes were defined as completely hypoechoic node, asymmetric focal hypoechoic node, cortical lobulation and cortical thickness >3mm)
• ultrasound-guided FNA cytology of these nodes were performed
• the result of FNA cytology was negative (no tumour cell was found)
• patient planed to perform SLNB

Exclusion Criteria:

• pathological diagnosed ductal carcinoma in situ by excisional biospy
• abnormal axillary lymph node was found by ultrasound examination but FNA cytology of these nodes were not performed
• the result of FNA cytology was positive (tumour cell was found)
• T4d tumour
• patient has recieved neo-adjuvant system therapy