Is skipped nodal metastasis a phenomenon of cutaneous melanoma?

Skipped nodal metastasis (SNM) is a recognized phenomenon of visceral cancers when metastases bypass the regional basin and skip to a distant nodal basin without evidence of distant metastases. Its occurrence is undocumented in cutaneous melanoma patients but of potential prognostic significance. We therefore assessed the frequency of SNM in a large series of patients with limb melanomas.

We studied melanoma patients attending a tertiary oncology hospital in northwest England using two approaches. First, we systematically searched medical records of an unselected patient sample treated 2002-2015, and second, we studied lymphoscintigrams of all patients with limb melanoma who underwent sentinel node biopsy 2008-2019.

Of 672 melanoma patients whose clinical records were examined, 16 had regional nodal metastases without apparent visceral spread and one appeared to have SNM but further scans were uncovered that showed concurrent pulmonary metastases. Of 667 limb melanoma patients with lymphoscintigrams, 7 showed dual lymphatic drainage patterns to distal as well as regional nodal basins, but none had micro-metastases solely in the distant basin.

Occurrence of SNM in cutaneous melanoma is highly unlikely.