Radio-guided ultrasound lymph node localization: feasibility of a new technique for localizing and excising nonpalpable lymph nodes ultrasound suspicious for melanoma metastases

Identification of lymph nodes suspicious for metastases is crucial in melanoma patients during the follow-up. We propose a procedure called radio-guided ultrasound lymph node localization (RULL) for melanoma patients with ultrasound (US) suspicious, not palpable, lymph nodes. The aim of this study was to evaluate the feasibility of this technique, and to assess the efficacy of this new method. RULL was applied in 12 consecutive melanoma patients with non-palpable lymph nodes found suspicious for metastases during US follow-up. Macro-aggregates of human serum albumin labelled with diluted technetium-99m were injected into the suspected lymph node under US guidance and followed by a scintigraphy. The surgical treatment was carried out with the support of hand-held gamma-probe used for sentinel node biopsy. The tracer was correctly positioned in all 12 patients. Pathological examination revealed seven patients with metastatic lymph nodes, four with no metastatic lymph node, one patient with Hodgkin disease. No surgical complications were described. In conclusion, RULL may integrate the standard ultrasound-guided fine-needle aspiration to improve the diagnostic accuracy on US suspicious nodes and might replace the more logistically complicated wire identification or less accurate cutaneous marker identification of these nodes. Sensibility and specificity of this approach should be defined through a large multicentric study.