Focal vitiligo is characterized by a few scattered macules. In some cases the depigmenation remains localized to these spots. For others, focal vitiligo can be a manifestation for general vitiligo.
Unilateral (segmental vitiligo)
In this case the patterns of depigmentatiaon involve small to large areas on one side of one's body. The patterns of depigmentation repeat from patient to patient. The prognostic is different from generalized vitiligo: the disease spreads for 1-2 year in the involved patch,and then the disease stops. There are rare cases where this type of vitiligo progresses to bilateral.
Acrofacial and Generalized vitiligo
This is the most common type of viitligo. It typically begins on the fingers and the feet, around the mouth and eyes. At this stage it is called acrofacial vitiligo. Most commonly it then spreads to involve the arms, neck, chest, genitalia and legs. It doesn't often involve the back or if it does, it is confined to a small area over spine. Generalized vitiligo can manifest itself at any age and it is recorded as early as 3 or 4 years old as well as late in life, at 70 years old. After onset, the disease progresses slowly and intermittently for many years. Other common areas it affects are: the face, neck, dorsal and ventral forearms, axillae, inner thighs and knees.
Vitiligo Vulgaris James J. Nordlund, I. Caroline Le Poole, and Raymond E. Boissy
Pictures: DermAtlas section on vitiligo