Rapid Immunohistochemistry for Cytokeratin in the Intraoperative Evaluation of Sentinel Lymph Nodes for Metastatic Breast Carcinoma

The sensitivity and specificity of detecting metastatic breast carcinoma in sentinel lymph nodes using a rapid immunohistochemistry technique was determined and compared with methods currently used at the authors' institution. At the time of intraoperative consultation, after routine diagnostic touch preparations and frozen sections were prepared, 6-microm frozen sections of 72 sentinel lymph nodes from 32 patients with breast carcinoma were placed on plus slides, fixed in cold acetone for 2 or 3 minutes, and stored at -70 degrees C. These sections were immunostained with a prediluted broad-spectrum anticytokeratin monoclonal antibody coupled to an inert polymer with horseradish peroxidase (DAKO EPOS). Slides were ready for interpretation within 16 minutes and were scored as positive, negative, or equivocal for metastatic carcinoma. Results were compared with those of the intraoperative touch preparations and frozen sections and with paraffin-embedded, hematoxylin and eosin-stained, and AE1/AE3 immunostained permanent sections. Fourteen (19%) sentinel lymph nodes were positive for metastatic carcinoma in 13 patients. All methods tested were 100% specific. The rapid immunohistochemistry method was the least sensitive (57% sensitivity) of all methods used to detect metastasis. Routine diagnostic touch preparations, frozen sections, and permanent sections had sensitivities of 69%, 86%, and 100% respectively. In conclusion, this rapid immunohistochemistry method would not be helpful in intraoperative assessment of sentinel lymph nodes in breast cancer patients due to its low sensitivity.