LAUSR

Sentinel lymph node (SLN) biopsy is typically offered to patients with primary cutaneous melanomas (PCMs) of ≥ 1 mm depth, but not all SLNs are positive using this cutoff. To ascertain whether positivity is genetically regulated, genetic analysis was performed using an augmented enrichment‐based next‐generation DNA and RNA sequencing assay in SLN‐negative (Group 1, n = 8, mean depth 1.3 mm) and SLN‐positive PCMs (controls, Group 2, n = 4, mean depth 1.4 mm). In Group 1, the mean number of mutations was 21 (range 3–48) with the most frequent mutations occurring in NF1 (75%) followed by TP53 (63%), CDKN2A and BRAF (38%), and NRAS (25%), while in Group 2, the ean number of mutations was 9.5 (range 5–18) with mutations in NRAS and BRAF being the most frequent (50%) followed by those in ATM, CDKN2A, CDKN2B, and NOTCH1 (25%). Increased frequency of NF1‐inactivating mutations in Group 1 provides provocative early data that the presence of NF1 mutations might confer a less aggressive phenotype.