Review Question - QID 108605

A 66-year-old man presents to the clinic for evaluation of a skin lesion on his hand. The lesion has grown rapidly over the previous 2 weeks. He endorses trauma to the area when he accidentally scraped his hand against a window and notes that there was some bleeding. His medical history is significant for chronic renal failure for which he received a renal transplant 5 years prior, as well as multiple surgeries for skin cancer. His current medications include aspirin, atorvastatin, prednisone, tacrolimus, and mycophenolate mofetil. His temperature is 98.6°F (37°C), blood pressure is 136/91 mmHg, pulse is 82/min, and respirations are 11/min. Physical exam is notable for a 2 x 2.5 cm nodular lesion of the dorsal hand as seen in Figure A. Which of the following is the most likely diagnosis?