<unk>  (also known as chloasma or the mask of pregnancy when present in pregnant women) is a tan or dark facial skin discoloration.  Although it can affect anyone,<unk>  is particularly common in women, especially pregnant women and those who are taking oral contraceptives or hormone replacement therapy (HRT) medications.The ratio of female to male is 9:1 and is  more common in yellow to brown skin color ( Fitzpatrick's skin photo type III to V) .The lesions usually develops in middle age and persists for many years. In post menopause women , the lesions usually fade spontaneously. Prolong exposure to sunlight is the most important etiologic factor. It is also prevalent in men and women of Native American descent (on the forearms) and in men and women of German/Russian Jewish descent (on the face).
Melasma
Icthyosis
Xanthelasma
Ichthyosis
Melanosis
Erythrasma
Onychophosis
Blue nevus