A man who ordered a Kindle was disturbed when he opened the package to find a tumour sample.
The Twitter user called James Potten, tweeted about his shocking discovery.
He wrote: "Wow @FedEx. You've swapped my new kindle with a tumor specimen. Still waiting for collection #FedExFail #notmykindle (sic)"
The parcel, clearly addressed to Mr. Potten was supposed to be sent to the Royal Free Hospital in London.
James told the BBC: "My name was on the outside, but the contents weren't what I expected. I haven't opened the sealed box, which says 'exempt patient tissue', as it doesn't belong to me. The tracking code on the item had the same first five and last three numbers as my order but it wasn't my Kindle."