Transection alone is not an indication for sentinel node biopsy in melanoma

The National Comprehensive Cancer Network (NCCN) recommends that sentinel node biopsy (SNB) be "discussed and considered" for any melanoma patient with a positive SNB (+SNB) risk of >5%. Several guidelines recommend SNB for transected (positive deep margin) melanomas.

We examined a prospective University database of patients who underwent SNB for clinically node negative melanoma. Patients with gross residual tumor at the initial biopsy sites were excluded from the analysis of T1 cases.

From 2011 to the present, 2142 patients underwent SNB for clinically node negative melanoma. 657 patients had SNB for T1 (thin) melanoma with an overall SNB positivity rate of 3.0%. 387 patients had T1b melanoma (>0.8 mm and/or ulcerated) with a +SNB rate of 4.9% (19/387). 270 had T1a melanoma and underwent SNB for a variety of indications, with a +SNB rate of 0.4% (1/270). In 57 cases transection of a shave biopsy was the only indication for SNB. Of these patients 52% were female, mean age was 60.2 years, mean thickness was 0.6 mm, and the most common tumor site was head and neck (35.1%). Nine (15.8%) had more tumor in the wide excisions but this did not upstage any patient; 4 had only melanoma-in-situ and 5 had residual invasive melanoma with a mean thickness of 0.5 mm. Of the 57, the mean number of SNs removed per patient was 2, and none were positive.

+SNB rates for T1a melanoma fall well below the NCCN cutoff to discuss and consider SNB. Transection alone is not a significant indication for SNB in melanoma when no gross residual tumor is found at the biopsy site.