Fast and sensitive immunodetection of carcinoma cells in sentinel nodes

In a number of clinical situations, especially in the context of the recent sentinel node concept, lymph-node involvement has to be determined intraoperatively. Since serious and dependable decisions are to be made according to the result of this examination, the most reliable method for the detection of tumour cells should be applied. We and others have shown previously that routine histological examination underestimates lymph-node metastases, and that immunohistochemistry (IHC) significantly improves the accuracy of staging. However, IHC has so far been difficult to apply to the intraoperative examination of cryosections since it has required too much time. We have developed a novel modification of IHC for the rapid detection of metastases of carcinomas in cryosections from lymph nodes. It is based on a unique directly labelled cytokeratin antibody, immunofluorescence, and a specially devised staining solution. This one-step staining procedure can be performed within 10 min. At the same time, its sensitivity is very high. Single tumour cells can easily be detected, and background staining is very low. The high sensitivity could result in a markedly improved reliability of sentinel node-based decisions.