Slow dynamic lymphoscintigraphy is not a reliable predictor of sentinel-node negativity in cutaneous melanoma

We reviewed data from 160 consecutive patients (89 M/71 F; 53.5 [range, 9-88] years) who had under-gone lymphoscintigraphy and sentinel lymph node biopsy (SNB) in our hospital for histologically proven cutaneous malignant melanoma (CMM) (located on the upper limb: 33; lower limb: 57; trunk: 44; and head and neck: 26 patients), with a Breslow index > 1 mm and without clinical or radiologic evidence of metastatic spread. Colloidal (99m)Tc-rhenium sulfide (36-76 MBq) was injected intradermally in the four quadrants around the tumorectomy scar, followed by dynamic acquisition and static imaging. SN(s) were identified in 157 patients (overall identification rate, 98%). Fast (< 20 minutes), intermediate (20-30 minutes), or slow (> 30 minutes) lymphatic drainage was observed, respectively, in 122 (78%), 24 (15%), or 11 (7%) cases. Overall malignancy rate was 15%, respectively found in 19 (16%), 2 (8%), and 2 (18 %) patients with fast, intermediate, or slow drainage. No statistical difference between SN-positivity rates of patients with fast (19/122 = 16%) versus intermediate or slow drainage (4/35 = 11.4%) was observed (p = 0.69). Therefore, lymphoscintigraphic SN appearance time in CMM patients is unable both to predict SN metastasis and spare them from undergoing SN excision.