Multiple Nevi on a Young Man

The teen presents for an annual physical. You note asymmetric papular lesions that cover his trunk. What is your diagnosis?

The images in Figure 1 above are of the anterior and posterior trunk of 16-year-old male who visits his primary care physician for an annual physical. His trunk is scattered with numerous asymmetric papular lesions with indistinct borders and variegated color; many are >6mm in diameter. Close-ups of several areas shown in Figure 2, at right.

What is your diagnosis?