Pigmentary disorders in oriental skin.

Brown hyperpigmented disorders may be melanotic in which there is a normal number of epidermal melanocytes but melanin pigment is increased in the epidermis (eg, melasma), melanocytotic, in which melanocytes are increased (eg, café-au-lait macules), and nonmelanotic hyperpigmentation (eg, minocycline pigmentation). Blue hyperpigmented disorders may also be melanotic in which there is a normal number of epidermal melanocytes, but melanin pigment is present in the upper dermis (eg, gray/slate pigmentation in Riehl's melanosis), melanocytotic in which melanocytes are present in both the epidermis and dermis (eg, blue pigmentation in Nevus Ota and Mongolian spot), and nonmelanotic hyperpigmentation in which pigment is present in the deep dermis (eg, blue pigmentation in tattoos). Hypomelanosis (leukoderma) may be divided histopathologically into melanocytopenic disorders on which melanocytes are absent (eg, Vogt-Koyanagi-Harada syndrome and vitiligo), melanopenic disorders in which melanocytes are present but melanin is reduced (eg, nevus depigmentosus and incontinentia pigmenti achromians), and nonmelanotic disorders in which melanin pigmentation is unaffected (nevus anemicus) and the pigmentary abnormality is caused by something other than melanin. There are numerous pigmentary disorders in the oriental skin, and some of them are either characteristic to or established in the orientals. Importantly, a number of congenital hypermelanotic and hypomelanotic diseases (eg, nevus depigmentosus, incontinentia pigmenti, and incontinentia pigmenti achromians, take a distribution following to the Blaschko's line.