Fig. 3

Punch biopsies of cutaneous lesions of the chest before (Panels a and b) and during (Panels c and d) systemic immunotherapy. Panel a shows a narrow-based compound melanocytic proliferation at low power (4×) with a few nests of melanocytes within the lower epidermis and a few melanocytes above the basal layer of the epidermis. In addition, there are nests of melanocytes within the dermis and mitotic figures are present among them. These features are consistent with metastatic melanoma. Panel b shows a high-power view (60×) of the melanocytes in the dermis, highlighting scattered dermal mitoses. Panel c shows a biopsy on treatment at low power (10×) with an area of complete regression of metastatic melanoma with dermal fibrosis and numerous melanophages. A high-power view (60×) of a Melan-A immunoperoxidase stain, shown in Panel d, does not show any labeling, confirming that there is no evidence of residual melanoma. Panel e shows the cytology smear from the inguinal node fine needle aspiration at 200×, with predominantly small unremarkable lymphocytes