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 be tween 1 to 17 years duration were examined under the electron microsco pe. 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 MC o were also observed in a few dermal cells in all vitiligo biopsies. A ll non-keratinocytes were scrutinized in series of 200-300 consecutive sections and were identified according to morphological characteristi cs. 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 detecte d in the epidermis it implies that the melanosomes can persist in cert ain KC for some time after the onset of vitiligo.