Derm Dx: Purplish spots on the scrotum

An elderly man with a distant history of malignant melanoma on his back presents to an outpatient dermatology clinic for an annual full-body skin exam. There are multiple purplish papules on his scrotum.

The patient is not aware these lesions were present, and therefore, he is unable to provide any relevant history. He denies pain or itch. The skin ...