We present two patients with stage IV
melanoma, the first with BRAF wild-type
melanoma with multiple visceral
metastases treated with
immunotherapy (
pembrolizumab) and the second with BRAFV600E
melanoma with subcutaneous and lymph nodes
metastasis treated with BRAF and
MEK-inhibitors (
dabrafenib/
trametinib). Already after the second cycle of
immunotherapy, the first patient developed a diffuse regression of
nevi, perceptible only with the use of dermoscopy and 3 months later a clinically evident poliosis of the eyebrows. The second patient, treated with
dabrafenib/
trametinib, developed small areas of leukoderma on his chest and white halos around
nevi with a dermoscopic globular or structureless pattern. Both observations are suggestive for an immune reaction against melanocytic cells, which is further supported by the complete response to systemic
therapy in both patients. It has been demonstrated that the development of
vitiligo-like depigmentation during
immunotherapy is associated with a better prognosis; in our patient, the phenomenon of poliosis appeared much later than the dermoscopic presence of regression among his
nevi, suggesting that the latter may be an early sign (along with
vitiligo-like phenomena) of good response to
immunotherapy. On the other hand, the development of
halo nevi and leukoderma during treatment with BRAF/
MEK-inhibitors, suggests that not only
immunotherapy but also targeted
therapy may induce an immunologic response against
melanoma and
nevi, again indicative of a favorable prognosis. More data are needed to confirm these findings; however, they indicate that dermatologists should be involved in the follow-up of patients with
melanoma, both in studies and clinical practice.