Word-for-word 'whitening disease':
白 'white' +
化 'to transform/-ify' +
病 'disease.' The
化 in the middle works like the English suffix '-ize' or '-ify,' so
白化 = 'to turn white,' and adding
病 makes it the medical condition. Same suffix pattern as
老化 'aging,'
美化 'beautification.'
