Sentinel lymph node dissection

Combined scintigraphic/surgical method for the detection and removal of the primary draining lymph node in the area of influence of a malignant tumor. The sentinel lymph node biopsy is currently performed for malignant melanoma from a tumor thickness of =/> 1.0 mm (for further indications see below, malignant melanoma ), for Merkel cell carcinoma and for high-risk spinocellular carcinoma of the skin (Note: The following information refers mainly to malignant melanoma, since this tumor has by far the most experience).

• The presence of metastases in the RLNs (regional lymph nodes) indicates that the tumour was able to spread. The SLND is suitable for detecting subclinical tumour progression.
• Metastasized tumor cells are detected histologically and immunohistologically by using appropriate antibodies.
• The RLNs should not be regarded as passive mechanical filters for systemic seeding of the metastatic tumor.
• As long as there is no effective adjuvant therapy for a metastatic tumour, close clinical controls and therapeutic/selective LK dissection are acceptable.
• According to the currently available studies, the SLN status in thick melanomas (tumour thickness > 4.0 mm s. Breslow index ) can be evaluated with sufficient certainty as a prognostic factor (significantly lower 5-year survival time in pos. LK infestation than in negative status). Furthermore, the SLN status plays an important diagnostic role in Merkel cell carcinoma and high-risk squamous cell carcinoma.
• SLND should be preferred to ELND (elective lymph node dissection) when prognostic information is required.
• In promising adjuvant therapies, the SLND can serve as an important prognostic factor.
• There is no sound scientific evidence that SLND followed by complete lymph node dissection improves the survival rate of melanoma patients (Breslow index 1.2-3.5 mm).

The primary draining lymph node detected by means of a lymph drainage scintigram and an intraoperatively inserted gamma probe is removed under local anesthesia and histologically, immunohistologically and molecularly biologically processed in cut series.

In many centers, a lymphatic dye (e.g. patent blue V) is injected into the tumor area preoperatively to additionally visualize the sentinel lymph node.

According to the results of clinical studies, SLND has proven to be an important predictive parameter.

Complications after SLND dissection can include: haematomas, lymphoedema, nerve injury, phlebothrombosis, bleeding and anaphylactic reactions caused by the (indicator dye).

The preparation of the sentinel lymph node should be evaluated according to national and international protocols (halving of the lymph node, at least 4 tissue sections per half, HE staining and additional immunohistological preparation ( Melan A, Ki 67, S100) by at least 2 experienced histopathologists.

• The prognostic relevance of tumor cell detection has not yet been clearly defined. With regard to the tumor burden, the following parameters should be included (applies to malignant melanoma):
• Length of the largest melanoma cell conglomerate
• Infiltration of the lymph node capsule
• maximum penetration depth of the melanoma cells into the parenchyma starting from the lymph node capsule
• Lymphangiosis - Accumulation of tumor cells in lymph vessels outside the lymph node.
• The diagnostic and therapeutic significance of lymphatic drainage of certain lymph node stations that are switched into the lymph drainage or upstream of it, such as the popliteal fossa in acral localized malignant melanoma, has not been conclusively clarified.
• The subfascially located, usually very small lymph nodes of the popliteal fossa drain the regions of the heel, the external ankle and the lateral calf. Popliteal lymph node metastases play a negligible role in clinical routine.

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