Comparison of immunohistochemistry with conventional histopathology for evaluation of sentinel lymph node in breast cancer.

The best method of pathological evaluation of sentinel lymph node in breast cancer has not been agreed upon. Immunohistochemical (IHC) techniques have shown a greater sensitivity over conventional histology for the detection of micrometastais. The aim of the study was to determine whether IHC for Epithelial Membrane Antigen (EMA) on the sentinel node could be more sensitive than conventional histology for diagnosing micrometastasis in sentinel lymph nodes. Eighty-four clinically node negative breast cancer patients underwent sentinel node biopsy at time of surgery for breast cancer. The node was subjected to conventional histopathology as well as IHC for EMA. The sensitivity of histology viz a viz IHC for EMA for detection of sentinel node metastasis was 88% and the specitficity was 96%. The overall diagnostic accuray of histology viz a viz IHC was 93%. There were 4 patients with micrometastasis (<2.0 mm), which were positive on IHC but negative on histology. Two patients with poorly differentiated breast cancer had a false negative IHC for EMA result as compared to histology. Immunohistochemistry for Epithelial Membrane Antigen can increase the detection rate of micrometastasis in sentinel lymph node. This can have important bearing on deciding the need of adjuvant systemic therapy. A false negative result for EMA may be seen in patients with poorly differential cancer. Therefore the best policy seems to employ both histopathology and IHC for EMA for the comprehensive evaluation of sentinel lymph node in breast cancer.