The image of the tapeworm cancer cells from the biopsy of the man's tumour. The malignant cells are pictured here. CDC

In a rare case, the lung tumours of a man who died from the cancer were caused by a tapeworm residing inside him. This is the first reported case of a person dying from a cancer of a parasite housed inside.

Researchers suspect that the patient in Colombia suffering from HIV did not have the immunity required for the body to kill the tapeworm. With both tapeworms and HIV being a widespread problem, there could be more such cases, warn the scientists.

"We have a unique case in an immuno-suppressed individual where he developed tumours where the cells responsible came from a tapeworm, so that they were indeed cancer cells, but derived from the tapeworm," lead author Atis Muehlenbachs, MD, PhD, staff pathologist at the CDC's Infectious Diseases Pathology Branch, told Medscape Medical News.

The cancerous cells eventually took over the man's body. It is not certain if such cancers can be treated with conventional drugs that tackle human tumours. It also raises concerns about cancer caught from the many resident microbes in a human body.

The man who turned up with fever and cough was sent to the CDC after biopsies of tumours in his lung and lymph nodes showed up strange cells. The cells were cancerous but the cell type was not human.

Unlike human cancer cells that multiplied, these cells not only multiplied but also fused. Finally the researchers found in the cells the DNA from a type of tapeworm called H nana. Three days following this discovery, the man succumbed. It is not clear hence if drugs for tapeworm infection help in treating such cases. H nana is the most common tapeworm in humans, infecting up to 75 million people worldwide. It is difficult to detect except by the presence of rice like grains in stool.

The study is published in the 5 November issue of the New England Journal of Medicine.