Man died with 'tapeworm tumours'

A man has died with tumours made of cancerous parasitic worm tissue growing in his organs, doctors report.

The patient had HIV and his weakened immune system allowed the worm-cancer to flourish.

The unusual case was diagnosed through a collaboration between the US Centers for Disease Control and the UK's Natural History Museum.

Doctors said the case, detailed in the New England Journal of Medicine, was "crazy" and unusual.

Colombian doctors had tried to diagnose the 41-year-old man in 2013.

He had what appeared to be normal tumours, some more than 4 cm across, in his lungs, liver and elsewhere in his body.

But on closer inspection the cancerous cells were clearly not human - they were tiny at just a tenth of the size of a human cell.

"It didn't really make sense," said Dr Atis Muehlenbachs, who picked up the "crazy" case at the US Centers of Disease Control.He ran through several theories including shrinking human cancer cells or even a newly discovered infection.

Eventually, molecular testing identified high levels of tapeworm DNA in the tumours and the reaction was "complete disbelief" from Dr Muehlenbachs.

He told the BBC News website: "This has been the most unusual case, it caused many sleepless nights.

"It should have been obvious this was cancer or an infection and not being able to tell between the two for months is unusual."

The patient was too sick to treat by the time doctors were able to identify the cause of his tumours.

He died, in Medellin in Colombia, three days after the worm DNA was discovered.