Sentinel node investigation in breast cancer: detailed analysis of the yield from step sectioning and immunohistochemistry.

AIMS To evaluate in detail the extent to which step sectioning and immunohistochemical examination of sentinel lymph nodes (SNs) in patients with breast cancer reveal additional node positive patients, to arrive at a sensitive yet workable protocol for histopathological SN examination. METHODS This study comprised 86 women with one or more positive SN after a successful SN procedure for clinical stage T1-T2 invasive breast cancer. SNs were lamellated into pieces of approximately 0.5 cm in size. One initial haematoxylin and eosin (H&E) stained central cross section was made for each block. When negative, four step ribbons were cut at intervals of 250 microm. One section from each ribbon was stained with H&E, and one was used for immunohistochemistry (IHC). RESULTS When taking the cumulative total of detected metastases at level 5 as 100%, the percentage of SN positive patients increased from 80%, 83%, 85%, 87% to 88% in the H&E sections through levels 1 to 5, and with IHC these values were 86%, 90%, 94%, 98%, and 100%. Three of nine patients in whom metastases were detected at levels 3-5 only had metastases in the subsequent axillary lymph node dissection. CONCLUSIONS Multiple level sectioning of SNs (five levels at 250 microm intervals) and the use of IHC detects additional metastases up to the last level. Although more levels of sectioning might increase the yield even further, this protocol ensures a reasonable workload for the pathologist with an acceptable sensitivity when compared with the published literature.