i think thay p has got more to do with stress than anything else.i was living in uk for 25 yrs,then decided to go to mauritius .i was under a lot of stress overthere and after a couple of years there got my first patch on my leg.i have been living there for 7 yrs now and the p has spread.it is quite hot here most of the year.in my case i know it has been trigerred by emotional stress then maybe exacerbated by other factors like diet,cold weather.