Purpose: To optimize the lymphoscintigraphic procedure in the staging of malignant cutaneous melanoma.
Material and methods: Fifty-five patients (21 men and 34 women) were enrolled. Breslow thickness of the lesions ranged 0.75-1 mm (Clark III-IV) to 1-4 mm. Lymphoscintigraphy was performed with a large-view gamma camera equipped with a low-energy general purpose collimator, two weeks after melanoma excision. A single perilesional dose of 30-50 MBq nanocoll-Tc99m (volume 0.2-0.3 mL) was injected 18 hours before surgery (6 hours in head localizations). After injection a gentle local massage was applied. A planar static scintigraphy (matrix 512 x 512, pre-set time 5 min) in anterior and/or oblique view(s) was obtained 5-10 min after radiotracer injection. The skin projection of the first node was stained with an external radioactive marker. Fifteen minutes before surgery a blue-vital dye was injected around the lesion. A radioguided biopsy of the sentinel node was performed.
Results: The site of the sentinel node was typical in 80% of patients. Two or three nodes were identified in 20% of patients. An unexpected node site was detected in 9% of patients. The total rate of micrometastasis to the sentinel node was 14.7% but significant differences were observed relative to the melanoma thickness.
Conclusions: Preoperative scintigraphy increases the accuracy of sentinel node identification in unusual lymphatic drainage pathways, in unexpected sites and in fast lymphatic drainage. Radioguided biopsy reduces surgical time, requires only local anesthesia and permits shorter hospitalization.