ABSTRACT
Pigmentation disorders occur as a result of an increased production of melanin by melanocytes and/or an elevated transfer of melanosomes from melanocytes to basal and suprabasal keratinocytes (1-3). Melanin (eumelanin and pheomelanin) results from the hydroxylation of tyrosine to 3, 4-dihydroxyphenylalanine (DOPA) through the enzymatic action of tyrosinase and the subsequent oxidation of DOPA to dopaquinone (4). Once produced, melanin is transferred to keratinocytes or into the dermis via any of the following processes: (i) damage to melanocytes in the basal layer allows for phagocytization by melanophages, releasing melanin into the dermis; (ii) melanosomes are directly deposited, through their dendrites, into the dermis; or (3) macrophages migrate into the epidermis where melanosomes are phagocytized, returning them to the dermis.
