Traditionally on May Day the fool plays at pratfalls and buffoonery around local morris dancers, brandishing his fool's bauble, an inflated pig's bladder on a stick, with which he bewitches and controls the crowds. To the uninitiated it looks like chaos, but for his own safety the fool must know the dances as well as anyone, so that his weaving tomfoolery meshes perfectly with the intricate pattern of kicks, handkerchief waving, and stickbashing.

In the newspapers on May Day, meanwhile, journalists were earnestly reporting the news that pig's bladder extract had been used by scientists in a major breakthrough allowing one man to magically regrow a finger. "'Pixie dust' helps man grow new finger," squealed the Telegraph's headline. "'Pixie dust' makes man's severed finger regrow," said the Times. "Made from dried pig's bladder," they explained, this magic powder "kick-starts the body's healing process".

Now firstly, if you look at the pictures accompanying this column, you will see from the "before" image that there is no missing finger, so we might naively intuit that there is no "missing finger grows back" story to be written. In fact, from the grainy images and scant descriptions available - despite blanket news media coverage, including television interviews - it seems this bloke lost about 3/8 of an inch of skin and flesh from the tip of his finger, and the nail bed is intact.

Make no mistake: I'd be whingeing a lot if it happened to me, but injured fingers do heal, sometimes badly, often nicely, just like gouges and scrapes on the rest of your body. "Nerves, tissue, blood vessel, skin" regrew, said the BBC. Yes. Up and down the country as we speak. The body is an amazing thing. If your experience of rollerskating injuries is not enough, Simon Kay, professor of hand surgery at the University of Leeds, saw the before-and-after pictures, and says: "It looked to have been an ordinary fingertip injury with quite unremarkable healing. This is junk science."

Where did this miraculous story come from? Dr Badylak is the scientist quoted in all of these stories. He told me: "This story came to the media not through us, but rather through the patient. I would just as soon it had not gone out until we complete our pilot study." That is unfortunate. I asked how this patient was recruited, what consent was obtained, how safety was assessed, whether this work has been published, and whether it will be published. He did not answer. Fair enough. He agrees that scepticism is understandable. I'm grateful.

The patient is Lee Spievack. He was given the powder by Acell, a large and longstanding biotech firm founded by Alan Spievack. He is Lee Spievack's big brother. Dr Badylak is Acell's chief scientific adviser, and he can be seen bravely making the best of all this unwelcome media attention by showing TV cameras around his labs and giving lengthy interviews, both now and in February 2008, when this story made the US news, and also, interestingly, in February of 2007, when it made the news for the first time, in exactly the same form, with exactly the same characters, and many identical quotes, verbatim, in the Wall Street Journal, MSNBC, and more. The injury itself, meanwhile, apparently happened (and healed) way back in 2005.

Reconstructing the media frenzy, it all seems to have kicked off - this time around - with BBC New York correspondent Matthew Price doing a very credulous set of interviews that went live on the BBC site on Wednesday at 3pm.

He nods endlessly and says "that's astonishing" when the company founder's little brother tells him that the tip of his finger healed. In the computer animation used by the BBC, a finger miraculously grows back more than half its length, at least two joints worth. At 11:30pm that same day the Press Association put out a story, but the newspapers must have had it sooner for the next day's papers, so I guess they lifted it from the BBC, too. By May Day 3:30pm the story was on Fox news (their morning), and by 11:30pm it hit ABC Australia. All used the same quotes in different permutations. And that's how news works.

Meanwhile, Dr Badylak now tells me that the entire nail bed was missing. This contradicts various previous news reports and apparently the pictures. He also says half the distal bone was missing. Confused? You should be. I've asked him for more pictures. I guess that just goes to show that the media is a confusing and inappropriate place to communicate new and unpublished epoch-making scientific breakthroughs (from 2005).

But we can console ourselves with the thought that one lucky company has had plenty of international media exposure. On three separate occasions. Over two years.

· Please send your bad science to bad.science@theguardian.com