Melanin and melanosome complexes in long standing stable vitiligo - an ultrastructural study

To investigate the presence of melanin and melanocytes (MC) in stable vitiligo, skin biopsies from five patients with vitiligo lesions of between 1 to 17 years duration were examined under the electron microscope. Areas of the upper dermis and epidermis were explored. There was a significant amount of melanin in a few keratinocytes (KC) grouped in the stratum basale in 1-3 year-old vitiligo lesions. In these KC, the melanosomes were most often aggregated into melanosome complexes (MCo) while the remaining KC were completely devoid of melanin. Solitary MCo were also observed in a few dermal cells in all vitiligo biopsies. All non-keratinocytes were scrutinized in series of 200-300 consecutive sections and were identified according to morphological characteristics. Neither active nor inactive MC, nor MC dendrites were found. These observations show that melanin in non-negligible amounts can be found even in 3 year-old vitiligo epidermis. Since there were no MC detected in the epidermis it implies that the melanosomes can persist in certain KC for some time after the onset of vitiligo.