What Causes Flat Lumps On Penis?

Hi
I have brown lump/spots on the head of my penis...
They don't itch or hurt etc
They have been there for a few years, (I just felt like ignoring it ) but I can't anymore , I don't know what they are and hoping you could give me an answer .
They seem to be a sort of pigmentation but if you look closely they look like spots
They are closely together and so look like a patch of spots/lumps ... Also I should add that I've never had sex