Indications for biopsy of imaging-detected intramammary and axillary lymph nodes in the absence of concurrent breast cancer.

To evaluate the prevalence of malignancy in imaging-detected abnormal lymph nodes (LNs) in women without concurrent cancer and to identify imaging features predictive of malignancy in this population. This is an IRB-approved study with waived informed consent. We retrospectively reviewed medical records of all image-guided LN FNAs and CNBs performed at our institution from 1/1/08 through 12/31/10. LNs sampled in patients without concurrent breast cancer comprised our study group (SG; n = 77), and with concurrent breast cancer our reference group (RG; n = 124). Blinded to cytology/histology, imaging features of the LNs including size, loss of fatty hilum, and cortical thickness were reviewed. A low/high suspicion category was then assigned based on LN appearance. The prevalence of malignancy in LNs in SG was 6% (5/77) and in RG 52% (64/124; P < .0001). Complete loss of fatty hilum had 100% (5/5) sensitivity, and 100% (56/56) NPV for detecting cancer in SG, compared to 39% (25/64) sensitivity and 61% (60/99) NPV in RG. When a "high suspicion" imaging feature was used as a threshold to biopsy, the sensitivity (5/5) and NPV (45/45) in SG were 100%, and in RG 78% (50/64) and 77% (47/61), respectively. The prevalence of cancer in imaging-detected abnormal LNs in patients without concurrent breast cancer is low. In the absence of concurrent cancer, using highly suspicious features of loss of fatty hilum or cortical thickness ≥ 5 mm as a threshold to biopsy will maintain high sensitivity with lower false-positive biopsy rate.