Complete sectioning of axillary sentinel nodes in patients with breast cancer. Analysis of two differenct step sectioning and immunohistochemistry protocols in 246 patients

Aims: To evaluate two detailed step sectioning protocols for sentinel lymph nodes (SLNs). Methods: After vital dye or combined dye and radiocolloid guided biopsy, SI.Ns were fixed in formalin and embedded in paraffin wax. In protocol A, SLNs from 123 patients were sectioned in steps of 50-100 pm, whereas in protocol B, SLNs from 123 patients were sectioned at steps of 250 Pm. Epithelial marker immunohistochemistry (IHC) was performed on multiple levels in cases with negative haematoxylin and eosin findings. Results: In groups A and B, 74 and 47 patients were found to have tumour cells in their oxillary SLNs, and 19 (28%) and 18 (19%) patients, respectively, were upstaged as compared with the standard histological assessment. Nodal involvement detected by deeper sections was often micrometastatic or in isolated tumour cells. Conclusions: Serial sectioning and IHC are recommended for the evaluation of SLNs. The optimal extent of the histopathological work up should be studied further.