I had to link to this article about a newborn that had surgery to remove a tumor. There was a foot and leg formed on the brain. Supposedly the baby is alright after the surgery.
Here is the link to the story which contains a picture of the foot and brain before removal.
Add www. before the above above for a working Url.
Sounds to me like there may have been two embryos originally and that one was semi-absorbed by the surviving twin.
Sad, freaky, but not at all unique really.
D’awwwwww, that’s such a cute little foot!
I guess it’s not a tumor.
I wish I had spare parts too.
The sparrows are flying.
Vanishing twin. Very sad and a little freaky. 
Au contraire. It may well have been a teratoma.
Apparently they missed seeing it ahead of time when they tested, so it was a surprise during surgery. Someone bring this to the attention of the writers for House.
I wonder if the pro life people would consider that an abortion. The fact that an embryo has no brain has never stopped them from considering it a human being, the leg-foot is still distinct and unique human life, at least more developed than an embryo cell. So is it an abortion thus forbidden by many religions?
Now if they could just effectively remove some people’s feet from their mouths.
I hope this experience sharpens surgical skills so it will be less painful the next time I need my foot extracted from my mouth – or if Red needs his foot extracted from Foreman’s ass.
They did one of these already, but they used chimerism.