I have this and I do several things for it that are not considered "primal". I get facial peels every to six months (VI Peel or Apeele) and use hydroquinone a few times a week. With the peel most of the pigmentation just comes right off. It just flakes and falls off. I have started using a better sunscreen so I’m not having as many issues now.
These kinds of things may work for you, but some people really want to keep away from chemicals at all costs (I even remember someone here asking about how to get rid of a life long tapeworm condition in a Primal manner LOL).
I have the same thing and it got worse recently when I began using topical estrogen and progesterone (I was applying the estrogen cream to my face, not the progesterone). I have stopped applying it there and while the melasma hasn't gone away, it hasn't become worse. So I pulled out my glycolic acid and have started with the DIY skin peels again to start sloughing away the discoloration gradually, and I wear sunblock on my face along with an SPF foundation. You can purchase glycolic acid or lactic acids from Amazon and work up to bimonthly applications, etc. Or, you can get a TCA peel and peel the stuff off in one application (it will burn quickly though and must be done after a lot of research, etc.). I don't recommend a TCA peel unless you've already had success with glycolic peels and are comfortable with it.