Contributors: Richard J. Grostern and Daniel M. Albert
Vitiligo is a chronic depigmenting disease that affects skin and other melanin containing structures such as the choroid, meninges. The lesions are frequently symmetrical. Vitiligo is probably an autoimmune disorder and patients often have antibodies to melanocytes. Vitiligo is sometimes inherited as an autosomal dominant trait. The depigmented regions completely lack melanocytes and the keratinocytes do not contain melanin. A sparse superficial perivascular lymphocytic infiltrate is present in keeping with the suspected immunologic origin. The depigmented areas may have an erythematous border and this is explained by an associated vasodilatation. The differential diagnosis of vitiligo includes hypomelanosis of Ito. Repigmentation occasionally occurs from the proliferation of melanocytes in hair follicles.
Vitiligo is a condition characterized by destruction of melanocytes, most likely of an autoimmune nature. Vitiligo is associated with ocular inflammatory diseases, most notably Vogt-Koyanagi-Harada syndrome, birdshot retinopathy, sympathetic ophthalmia, uveal melanoma, as well as with other ocular depigmentations. The prevalence of vitiligo is frequently cited as 1%, although figures vary between 0.1% and 8.8%. There is probably no racial or sexual preponderance. Approximately one third of affected individuals has a family history of vitiligo. Children of affected parents have a 4-5% chance of also being affected. Onset is usually in the second or third decades.
A number of theories exist proposing possible mechanisms for the occurrence of vitiligo. The most common theory suggests an autoimmune mechanism, although it almost certainly is not as simple as autoantibodies. There is likely a neurochemical component as well, as evidenced by the lack of vitiligo on paralyzed limbs. Genetic theories exist, as well as an autocytotoxic theory of melanocytes. Chemical exposure to certain thiols, phenols, derivatives of catechols, mercaptoamines and several quinones is known to increase the risk of vitiligo.
An absence of melanocytes in lesional skin is the predominant histopathologic finding. In the earlier more inflammatory stages a moderately intense mononuclear cell and mast cell infiltrate is sometimes seen. There are no ophthalmic pathologic studies of eyes with vitiligo, other than those severely affected by Vogt-Koyanagi-Harada syndrome. The presumption is of a similar loss of melanocytes in affected areas, within the retinal pigment epithelium and the choroid.
The size, number, and location of skin lesions is highly variable. They may occur anywhere on the body. Lesions increase in size by peripheral extension. There is no longitudinal study of ocular lesions.