I Have A Dark Unraised Spot On My Penis. It

I have a dark unraised spot on my penis. It seem to start/ spread from the dark circumsision ring and spreads toward my body. It had faded at times and then appear more prominent after sex. Never any pain. I had a biopsy last year and dermatology said they where sun or age spots. Is there a recommended medicine, cream or procedure to lighten or remove these spots?