Clinical classification of vitiligo Classification system is important because of the special significance assigned by some authorities to each type of vitiligo. This classification system provides for distribution of vitiligo lesions. Considering the aspects of progression, prognosis, and treatment, vitiligo also can be classified into 2 major clinical types, segmental and nonsegmental. Segmental vitiligo usually has an onset early in life and spreads rapidly within the affected area. The course of segmental vitiligo can arrest and depigmented patches can persist unchanged for the life of patient.
Nonsegmental type includes all types of vitiligo except segmental vitiligo.
Four pathogenic theories have been discussed. Immune hypothesis Aberration of immune surveillance results in melanocyte dysfunction or destruction. A neurochemical mediator destroys melanocytes or inhibits melanin production. An intermediate or metabolic product of melanin synthesis causes melanocyte destruction. Genetic hypothesis Melanocytes have an inherent abnormality that impedes their growth and differentiation in conditions that support normal melanocytes.