Metastatic Uveal Melanoma to Liver

A 62-year-old man with a history of left ocular choroidal melanoma treated with enucleation 6 years ago presents with right upper quadrant pain, weight loss of 12 kg, and massive hepatomegaly. Laboratory investigations reveal markedly elevated alkaline phosphatase (940 U/L), elevated GGT, mildly elevated bilirubin, and serum LDH of 780 U/L. CT abdomen shows innumerable hepatic lesions. At autopsy, the liver specimen demonstrates the structures marked **D** — jet-black pigmented nodules studding the hepatic capsule and cut surface, ranging from 0.5 to 5 cm. Which of the following best explains the pathological findings and the characteristic appearance of these lesions?