Histological regression in primary melanoma and drug-related immune reaction towards metastatic melanoma: Are they associated??

Histologic regression has recently been associated with a more favorable prognosis in primary melanoma. historically this immune phenomenon was described as a negative prognostic factor able to substage the true Breslow thickness. Since many years we have assisted to the appearance of vitiligo in metastatic melanoma patients. This has been considered one of the explanations of the immunogenicity of this disease, as inducing a strong immune reaction against cancer cells able to kill normal melanocytes even far from the metastatic lesions, This vitiligo like reaction has been seen even stronger in patients treated with immune and target therapy. The three phenomena involve the same pattern of lymphocytes. The association between the three can explain the better prognosis of the patients with primary melanoma with histological regression as well as the longer survival of the vitiligo like immune reaction in metastatic melanoma patients.