......Michael had vitiligo, a pigment disorder. .....
Get real, he was sujected to repeated prolonged dose or submersion to extremely strong whitening agents. The disease you mentioned is a smokescreen to cover his real treatments. It’s called plausable deniability
http://www.npgandour.com/english/fichiers/soinscorps/bioclair.html
The active ingredient of these cremes manufactured and widely sold in Africa is the chemical hydroquinone. In America the FDA limits the compound strength to 2% but mothing prevents a quack, or perhaps a Swiss quack, from purchasing easily available hydroquinine and mixing his own. This wiuld be especially true if a vanity obsessed man with zillions offered eonugh money.
Yes he stayed true to his family (in a way) to his mother and Dianna Ross, but in his own way Mjj reject everything black...His skin, his wives, his children, even the lawyer and business managers that he trusted with his will are white.