Sentinel lymph node detection in primary melanoma with preoperative dynamic lymphoscintigraphy and intraoperative gamma probe guidance.

Abstract

This study assessed the value of the radioisotopic method used alone, and factors influencing relapse rates, for sentinel lymph node (SLN) mapping in primary melanoma. One hundred and thirty-three patients with a diagnosis of melanoma (thickness greater than 0.75 mm) underwent gamma probe-directed lymphatic mapping in a prospective single-centre study. Mean Breslow thickness was 3 mm. At least one SLN was identified in 132 patients (mean 1.8 nodes per patient); the success rate was 99.2 per cent. Twenty-two patients (16.7 per cent) had a metastasis within the SLN. The mean tumour thickness in patients with a metastatic SLN was 4.4 mm compared with 2.7 mm for patients with a negative SLN (P < 0.001). The median time to recurrence was 20.4 months in SLN-negative patients compared with 8.5 months in those with SLN metastasis (P < 0.001). Ten (9.1 per cent) of the 110 SLN-negative patients developed recurrence. Three patients relapsed in the previously mapped lymphatic basin after a median follow-up of 27.1 months. This study confirmed the reliability and accuracy of SLN mapping using a radioisotope technique, and also the importance of the SLN as a predictive factor for survival. There was a low risk of locoregional recurrence when the SLN was not involved.