Vogt-Koyanagi-Harada disease and vitiligo: Where does the illness begin?

Abstract

Vogt-Koyanagi-Harada (VKH) disease is a disorder affecting melanocytes of the skin, ocular, auditory and central nervous system. The pathogenesis is thought to be related to an aberrant T cell-mediated immune response directed against self-antigens present in melanocytes. Vitiligo is characterized by leukoderma arising at any age but usually before 30 years of age. The pathogenesis of vitiligo still remains puzzling; many hypotheses have been proposed, such as autoimmune, genetic, autocytotoxic, neural and each may contribute having its own important pathogenetic role. The expressions of the most representative melanocytic markers as HMB-45, tyrosinase, S-100 protein were investigated on the lesional, perilesional and healthy skin of a patient affected by VKH and his young daughter with vitiligo. An electronmicroscopy (EM) study was performed on the same clinical specimens. Immunohistochemical data for melanocytic cells using HMB-45 and tyrosinase were negative in the VKH patient, while the expression of both HMB-45 and tyrosinase was detected in the perilesional and lesional skin of the vitiligo patient. By EM, it was possible to show many Langerhans cells (LC) in many differentiative phases, most of which with irregular cristae or matrix swelling in both the ultraviolet (UV)-exposed and non-UV-exposed skin of VKH lesions. In both vitiligo and VKH lesions, there is a disappearance of melanocytes and an alteration of LC distribution and mitochondrial morphology which may impair the antigen-presenting functions. The vitiligo lesions in the patient's young daughter question the VKH inheritability.