SLN Investigation by Pathologists in Cooperation with Cytopathologists

In recent years the "working formula" has been: When pathologists investigate the SLN intensively and do not find any metastatic settlement investigation of the other approximately 12 lymph nodes (average in German breast cancer studies) or even more (usually after revision of the axilla) can be omitted.

This is only partly correct, and mostly emanates from nonpathologists.

It must be stated that investigation of the sentinel node means work-up of a large number of serial sections stained alternately with HE and immu-nohistochemically, using antibodies directed at cy-tokeratin (Fig. 5).

In view of the heavy responsibility resting on anyone stating that the SLN is really negative, a large number of sections must also be stained im-munohistochemically and evaluated microscopically by qualified pathologists.

In addition, in the case of positive results of the sentinel node investigation, 12 or even more lymph nodes must be paraffin embedded and also evaluated histologically in addition to appraising the status and classifying it according to the TNM-system in view of the exact N-status.

The thesis that serial sectioning of one or two SLNs with HE and cytokeratin stainings takes less time than sectioning of a dozen or some more nodes after axillary revision is not fully correct, because

Handling of Histopathological Procedures 95

Fig. 5. Segment of a lymph node near to the subcapsular region, showing disseminated single cancer cells stained (red) for cytokeratin. The typical epithelial cell layering is missing. The epithelial cancer cells cannot be detected with certainty in normal HE stainings and cannot be differentiated from reticulohistiocytic cells

Fig. 5. Segment of a lymph node near to the subcapsular region, showing disseminated single cancer cells stained (red) for cytokeratin. The typical epithelial cell layering is missing. The epithelial cancer cells cannot be detected with certainty in normal HE stainings and cannot be differentiated from reticulohistiocytic cells

• Pathologists bear a much heavier responsibility, especially in breast cancer cases, because false-negative results caused by insufficient investigation of the node(s) can lead to axillary recurrence with a fatal outcome.

• Before introduction of the sentinel node concept pathology laboratories brought three or more lymph nodes in a single paraffin block for serial sectioning.

Preparation of such a large number of serial sections as dictated by the sentinel node concept was not recommended or even considered. This state of affairs was acceptable insofar as if single tumor cells were not detected in the first node reached by the flow of lymphatic drainage all secondary nodes at levels I and II were already prophylactically removed according to the principles of extended axillary revision.

Altogether, the responsibility for the assurance that sentinel nodes are genuinely tumor-free has become considerably heavier, but the investment required for the investigations is no lower in terms of time or cost.

In total, the new procedure followed since adoption of the sentinel node concept demands more manpower than the conventional staging investigations. Therefore, following the introduction of these new and certainly helpful investigative principles, new ground rules on financing the manpower needed and the cost-intensive immunohisto-chemical staining must be established in every country. Otherwise, these intensive diagnostic efforts cannot correctly be carried out. This is a ser ious warning and should be heeded in order to avoid later litigation against clinics and the medical staff working in them.

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