Melanocytes are cells of neural crest origin. In the human epidermis, they form a close association with keratinocytes via their dendrites. Melanocytes are well known for their role in skin pigmentation, and their ability to produce and distribute melanin has been studied extensively. A close contact between melanocytes and nerve fibers in the epidermis has been demonstrated in normal human skin. In patho physiology of certain dermatoses interactions between the neural and immune systems play an important role.
In this study, we investigated the intraepidermal nerve fibers and their contacts with melanocytes in the lesions of melasma using double labeled immune fluorescency and confocal laser scanning microscopy. We found that the percentage of contacts between intraepidermal nerve fibers and melanocytes in the lesion of melasma were 74%, significantly more than the 42% in the normal controls (p<0.05). The difference in the number of neural-melanocytic contacts between the lesional and normal-appearing skin of the melasma patients was also statistically significant (p<0.05). Melasma is an acquired circumscribed facial hyperpigmentation commonly seen in Asian women. A number of anecdotal clinical observations have shown that when the melasma patients are physically exhausted or emotionally distressed, the facial skin hyperpigmentation becomes more obvious.