Subcutaneous metastases from melanoma: a discussion of clinical experience

The majority of locoregional relapses of cutaneous melanoma occur as subcutaneous local recurrences/in-transit metastases; subcutaneous metastases (SMs) are also common in distant metastases. SM therapy is challenging and depends on the number, site, depth, size, clinical behavior and presence of other metastases. Isolated, resectable SMs should be treated surgically. In multiple/unresectable lesions, several local modalities are used: carbon dioxide laser ablation, radiotherapy, cryotherapy, intralesional injections and electrochemotherapy. Hyperthermic isolated limb perfusion is the preferred method of treating multiple, bulky in-transit metastases in extremities, allowing for high response rates and long-lasting remission. Electrochemotherapy is a simple method for the fast ablation of SMs that are not feasible for hyperthermic isolated limb perfusion. Recent advances in systemic therapy of melanoma, including immunotherapy (anti-CTLA4/anti-PD-1) and targeted therapy (BRAF/MEK inhibitors), have significantly impacted on SM treatment. We present our own SM cases treated with different modalities. The future of SM therapy will rely on a combination of different local, locoregional and systemic modalities, and we can expect major improvements in long-term outcomes.