I just saw a report on Deutsche Welle health program about the use of pseudocatalase cream combined with short duration UVB exposure. The Insitute for Pigmentary Disorders, in Greifswald, Germany, has had good results with this treatment. Their website says that natural catalase cannot penetrate the skin, and not to trust the effectiveness of creams containing natural catalase. They also advise patients not to consume turmeric, as it can prevent the pseudocatalase from working. Turmeric has a lot of health-giving properties, so this is a shame.
Another piece of advice was that people with vitiligo are more at risk of getting skin cancer, and should have a full skin examination once a year.
Here's a link to the Institute website (obtained from the DW website).
A forum thread on this topic: