Sentinel lymphadenectomy in cutaneous melanoma

In the last ten years validation of the sentinel lymph node (SLN) concept has led to modification of the surgical approach for patients with intermediate-risk cutaneous melanoma.

Forty-eight patients affected by cutaneous melanoma with a Breslow thickness between 0.65 and 4 mm were enrolled in the study. Approximately 2 mCi of radiotracer and 1 mL of vital blue dye were injected in each patient around the site of the primary lesion. Lymphoscintigraphy was performed until the lymphatic basin and the respective SLN were localized. The whole surgical procedure consisted of enlargement of the surgical margins followed by localization and excision of the SLN(s) by using both radiotracer and vital dye. Whenever the SLN proved to be histologically positive for metastasis, complete regional lymphadenectomy was performed.

Within 15 minutes of radiotracer administration the lymphatic basin was localized in all 4 patients by lymphoscintigraphy. Vital dye and radiotracer successfully allowed SLN localization and excision in 46 of 48 patients (97%); in one case the SLN was detected by radiotracer alone. The SLN proved to be metastatic in six (13%) of 46 evaluable patients; interestingly, in three of them the presence of metastatic cells was revealed only by immunohistochemistry. All patients with tumor-positive SLNs had primary lesions with a Breslow thickness = 2 mm.

Sentinel lymphadenectomy is able to identify lymph node involvement in patients with cutaneous melanoma with a Breslow thickness > 1 mm, thus avoiding the risks associated with radical regional lymphadenectomy. Lymphoscintigraphy proved to be an important tool to obtain correct preoperative localization of the drainage basin, especially for melanomas located on the face and trunk.