A 42-year-old Amish man presents to your primary care clinic after noticing an irregularly shaped 3 cm long, 2 cm wide lesion on the right side of his lower neck. He reports that he has this mole for a few months and it has recently changed color from a light brown to a dark reddish purple. It now seems to be more raised than it used to be. It is changing its shape and size. He works in his agricultural farm raising horses, chicken and growing alfalfa under outdoor sun. In the physical examination, you notice a poorly defined, irregular, hyperpigmented, multicolored mole on the right side of his neck. As shown in the figures, the biopsy of the lesion demarcates nests of atypical pigmented cells. The molecular genotyping of the lesion reveals the presence of a BRAF V600E mutation. Of the following, what is the most likely diagnosis?
