Sentinel node

Indications

Tumor depth is ≥ 0.8 mm (if 0.75 mm, round up to nearest decimal = 0.8 mm)

Ulceration

Tumor depth is not possible to measure

Uncertainty of primary tumor or metastasis (and no distant metastasis on PET-CT)

Sentinel node and pregnancy

Sentinel node and scintigraphy is possible also for pregnant women. If the site of injection is close to the uterus (< 10 cm), the quantity of activity should be reduced, with a short interval to surgery. Methylene blue should not be used.

Contraindications

It is unnecessary when a patient presents with systemic disease. Similarly when a patient presents with a clinically evident node.

For patients who have previously undergone sentinel node, there is nothing in the literature to establish definitive recommendations.

Sentinel node procedure

Injection of patent blue at the primary tumor site

Probe pinpointing position of sentinel lymph node by a radioactive tracer

Sentinel lymph nodes are removed assisted by radioactive agent and patent blue

The sentinel node is indicated by the scintigraphy. The typical localization for the sentinel node is for;

Extremities: toward node basins either in the axilla or groin.

Truncal region: can go to multiple nodal basins (axilla or groin).

Head and neck: follows the seven levels of head and neck

Sentinel node procedure from the groin

The sentinel node area (right groin) is identified at the scintigraphy. A search is then first conducted in the groin area. When the probe alerts the sentinel node, a marking is made.

Afterward, a small incision is made, and the sentinel node is removed. After removing the node, the probe is used to confirm. Then the probe is used to search for the remaining radioactivity in the area. The maximum remaining radioactivity accepted is 1/10 of the sentinel node (e.g. SN = 800, remaining activity of 80 is accepted).

Step 1: Prior to incision

Radioactive agent is traced percutaneously prior to the incision. The incision is marked by pen.

Step 2: Incision

A conservative incision is performed. Dissection continues until division of the fascia.

Step 3: Radioactive tracing

After division of the fascia the sentinel nodes are sought out assisted by the radioactive agent and patent blue colouring of the lymph vessels.