[In-transit sentinel lymph nodes in malignant melanoma. What is their importance?]

The sentinel lymph node (SLN) is the first node in a lymph node basin to receive direct drainage from the primary tumour. However, in some cases, lymphoscintigraphy images demonstrate the presence of lymph nodes located in the area between the primary tumour and the first regional lymph node basin. These nodes are called in-transit nodes and have to be considered SLNs as well.

It was to determine the incidence and location of in-transit SLNs in patients with malignant melanoma and to evaluate whether it is necessary to harvest them. METHOD. Nine hundred patients with malignant melanoma were included. Lymphoscintigraphy was performed on the day before surgery following intradermal injection of 74-111 MBq of 99mTc-Nanocolloid in four doses around the primary lesion or the biopsy scar.

The presence of in-transit SLNs was revealed in 80 patients. During surgery, in-transit SLNs were identified and excised in all but 3 patients (96.2 %). Metastatic cell deposits were identified in these in-transit SLNs in 15 patients (19.4 %), with 4 patients with no tumour involvement of the regional lymph node basin.

Lymphoscintigraphy is mandatory in the location of in-transit SLNs. Moreover, although the incidence of these nodes is relatively low in malignant melanoma, the presence of metastatic cells in these in-transit SLNs reaches a significant percentage. Therefore, excision of in-transit SLNs is necessary in all cases.