MORPHOLOGIC OBSERVATIONS ON THE DERMAL NERVES IN VITILIGO: AN ULTRASTRUCTURAL STUDY

Abstract

Vitiligo is a common idiopathic skin disorder. The etiology is unknown, although various hypotheses have been advanced. These include the neuronal hypothesis, where neuronal factors are thought to play a role in the pathogenesis of this disease. Skin biopsies were taken from marginal and central parts of four vitiligo patients. Biopsies were also taken from nonvitiliginous skin of each patient and from four normal control subjects. Sections were examined under the electron-microscope. Nerve fibers in the superficial dermis were examined. Subtle ultrastructural changes, including regeneration and degeneration, were consistently found in dermal nerves of vitiligo lesions. The most consistent feature, seen in all four vitiligo patients studied (in both lesional and marginal areas), was an increased thickness of the basement membrane of Schwann cells. This change was found in approximately three-quarters of all dermal nerves in vitiligo biopsies, but in only about one-quarter of dermal nerves in normal control skin. About half the abnormal dermal nerves in vitiligo skin showed minor axonal damage, although indicators of regeneration (increased mitochondria and rough endoplasmic reticulum) predominated. The dermal nerves in vitiligo showed no difference in fiber diameter or fiber density in comparison with controls. In vitiligo both axonal degeneration and nerve regeneration may occur, with the latter possibly being a reactive change to earlier axonal damage. These findings support the hypothesis that there is a neuronal component to this disease.