How to cure what they call pregnancy mask?

Some creams but, : If you are pregnant, it usually goes away delivery. Otherwise there are over the counter and prescription fading creams. If cream is used, use thin even layer and avoid sun exposure.

No cure but..: There are several treatment options including the use of creams like hydroquinone & retin-a, glycolic or Alpha hydroxy peels, laser treatment for dermal and mixed-type melasma, avoidance of uv light exposure and using sun screen. Outcome is dependent on type of skin, responsiveness to treatment, sticking to a daily skin care regimen, and avoidance of sun exposure.

Control not cure: The most effective management of "mask of pregnancy" or melasma is combination therapy which may include topical agents to help exfoliation and decrease pigment production (skin lighteners), peels, laser treatments. Melasma treatment can be quite challenging, so patience is key. Consult with a cosmetic surgeon or dermatologist with expertise in dealing with melasma or pigment disorders.