What is the name of the skin disease whereby a person's skin discolours and turns to white-tish pink overtime?

Answer 1

Not sure about white-tish pink, but white patches is Vitiligo.

Answer 2

There are over 175 causes for skin to discolour. Of them all, Vitiligo is more often the cause.Vitiligo is a skin condition resulting from loss of pigment; white discoloration / depigmentation, the milky white patches can appear on any part of the body. The pigment responsible for skin colour is called melanin. When cells are not able to produce melanin, white patches are clearly visible. The condition does not seem to harm the body but it produces stress and psychological discomfort, especially among children and teen-agers. Traditional medicine, does not seam to be able to cure or to control this condition. It is estimated that over 1% of population is affected by this condition.
I add a link which contains details of vitiligo

http://www.skinsite.com/
info_vitiligo.htm

Hope this helps
Matador 89