Dark Patch on Upper Lip - What would cause this?

[Virgo]

Over the past few months I've been developing a dark area on my upper lip. It's exactly where a man's moustache would be, except that the area is not hairy. I'm very careful about using sunblock, so I don't think that can be the problem either. Also, it's a solid dark area, not little sun spots.

Any ideas for what the cause could be? Also for treatment of the problem? (I don't have dark patches anywhere else.)

[orangehrzn]

It could be melasma or maybe fungus.

[Serbon]

Would be interesting to know when it occurred. Are you pregnant, have you changed contraceptive, have you recently undergone a major stress in your life, have you recently had an upper lip wax or laser hair removal and if so what was used post treatment and where you in the sun after a treatment even with sun protection? Does your sunscreen cover a broadspectrum? It is really helpfull to determine a treatment pathway if you can pinpoint a "trigger"