Vitiligo is a condition of the skin caused by a failure in the auto-immune system. One's natural pigment is destroyed and the skin becomes white. I have both Psoriasis and Vitiligo but a Search of this site threw up only three hits for the latter, suggesting that few P sufferers have it. That, in turn, would suggest that the two are not linked.
I have no reason to suggest that they are. P runs very strongly in my family and I can trace my vitiligo back to an emergency dose of antibiotics given when I was a sheep breeder and had contracted orf from a sheep. (there is a theory that a high dose of antibiotics can harm the auto-immune system and cause vitiligo) I thought, however, that it would be interesting to ask the question of whether the incidence of vitiligo in the psoriasis population (as represented by members of this site) is any greater than the incidence in the population as a whole.
Are there whities out there?
Bill