Blue nodes left behind after vital blue dye-guided axillary sentinel node biopsy in breast cancer patients

Background: Vital dye-guided sentinel node biopsy is affordable in most hospitals, but may be of limited accuracy in identifying all sentinel nodes. Leaving sentinel nodes in the axilla may result in a false nodal staging of breast carcinomas. Methods: From a series of 112 successful sentinel lymph node biopsies with Patent Blue dye followed by axillary dissection, 10 cases were identified where 1-3 blue nodes were found in the axillary dissection specimens. These 10 cases were compared with those which had all blue nodes identified during surgery. Five of the 10 patients with missed blue nodes also underwent lymphoscintigraphy with 99m-Tc-labeled colloidal human albumin and all of their nodes were subjected to external gamma well counting postoperatively. Results: There were six false-negative sentinel lymph node biopsies overall, but none in patients with missed blue nodes. Patients with primarily unidentified blue nodes had more sentinel nodes and a higher rate of multiple sentinel nodes than the others. Conclusion: Blue nodes missed during surgery may be either true sentinel nodes or second echelon nodes labeled by dye overflow. This type of error may occur in <8% of patients and may lead to false-negative sentinel node-based staging in an even smaller proportion of cases (none in this series).