A UK man who ordered an electronic reader was somewhat taken aback to discover that the courier service had instead delivered him a human tumour sample instead.

Bristol local James Potten, a fellow apparently given to understatement, told the BBC he got "quite a shock" when he opened up the FedEx package late last week and found a lump of cancer instead of his Kindle.

Definitely not a Kindle. (Twitter)

"My name was on the outside, but the contents weren't what I expected," he told the news service.

"I haven't opened the sealed box, which says exempt patient tissue, as it doesn't belong to me," Mr Potten said, adding that he was worried that the tumour sample – meant for the Royal Free Hospital – may have been needed urgently.

"The tracking code on the item had the same first five and last three numbers as my order but it wasn't my Kindle."

"Shocked"...James Potten.

FedEx, which had managed to deliver the Kindle to the hospital, said it "regretted the error" and would review its processes.