Quoting wikipedia:
Jackson's skin had been a medium-brown color for the entire duration of his youth, but starting in the mid-1980s, it gradually grew paler. The change gained widespread media coverage, including rumors that he might be bleaching his skin. According to J. Randy Taraborrelli's biography, in 1986, Jackson was diagnosed with vitiligo and lupus; the vitiligo partially lightened his skin, and the lupus was in remission; both illnesses made him sensitive to sunlight. The treatments he used for his condition further lightened his skin tone, and, with the application of pancake makeup to even out blotches, he could appear very pale. Jackson was also diagnosed with vitiligo in his autopsy.
1) Is this plausible?
2) Is it likely to be an actual disease, or would there be so many mitigating factors that it is unlikely a person would suffer to the extent he did?