(NSFW) Is there a word for the dark brown flesh that many of us have surrounding our anus?

The subject of skin bleaching came up on TV yesterday, and it sent me to Google for information on it. Among the links returned, I stumbled across a one to a Q&A site where someone was asking how she could bleach the “stain” away from her anal area. I do not think it’s a stain. As far as I know, it’s just a darker area of flesh and is quite normal, particularly for people with a fair amount of pigment in their skin. I certainly don’t see it as something that needs bleaching.

But I was struck by the discussion. While everyone knew what she was talking about, and a few mentioned that high-end spas do offer such bleaching and that some porn stars have had it done, nobody seemed to have a word for this body feature.

Am I right that it is normal pigmentation and not a stain? Just about every other conceivable body feature in humanity has a name. Does this one too? Have I led such a sheltered life that it just escaped me? Or is it so taboo that we can’t even have a word to use in discussing it?