Lime+Sunglight=Pigmentation

I noticed patches of redness on my left hand the other day. I went to the doctor yesterday for my allergies, and also asked him to look at the discoloration of my hand. He briefly looked at it, and he asked the most bizarre question (I thought)- Did you use lime last week? I was like, huh? Err.. yeah, I did. How did u know? Then, he asked, did I go out in the sun after that? I was like, I don't know, I can't remember, I might have gone out for a run. Then, he told me something I didn't know before this - I must have gotten some oils from the the lime onto my skin, and it was exposed to the sun, and thus a photochemical reaction occured, causing the skin discoloration. It will go away, eventually. (I hope that's true) Interesting, isn't it? So for future references, please wash your hands thoroughly after working with limes! :)