Outline
Health warning circulating in the form of a graphic claims that using a laptop computer across your legs can cause a heat-related condition known as ‘toasted skin syndrome’ that may lead to skin cancer.
Brief Analysis
Toasted skin syndrome is a real condition and medical reports indicate that using a laptop across your legs can indeed cause it. The condition can also be caused by exposure to heat from other sources such as heat packs and hot water bottles. And, in very rare cases, the condition can cause damage leading to skin cancer. The image used in the graphic is taken from a medical article on the condition and the case depicted was due to the prolonged use of a heating pad applied for joint pain rather than a laptop.
Example

Do you have a laptop? Beware!!!
Extreme heat from laptop can cause TOASTED SKIN SYNDROME
May finally lead to SKIN CANCER
WARNING STOP UISNG LAPTOP OVER THE LEGS
MUST SHARE THIS
Detailed Analysis
According to this warning, which travels the highways and byways of cyberspace in the form of a graphic, using a laptop across your legs can cause a heat-related condition known as ‘Toasted Skin Syndrome’.
The message includes an image depicting a case of the condition described and warns that the condition may finally lead to skin cancer. The message advises people to stop using laptops across their legs and asks that recipients share the information so that other laptop users will also be warned.
In fact, Toasted Skin Syndrome is a real condition and it can indeed be caused by heat from laptop computers. An October 2010 Sydney Morning Herald article on the issue explains:
In one recent case, a 12-year-old boy developed a sponge-patterned skin discolouration on his left thigh after playing computer games a few hours every day for several months.
“He recognised that the laptop got hot on the left side; however, regardless of that, he did not change its position,” Swiss researchers reported in an article published today in the journal Pediatrics.
Another case involved a Virginia law student who sought treatment for the mottled discolouration on her leg.
Dr Kimberley Salkey, who treated the young woman, was stumped until she learnt the student spent about six hours a day working with her computer propped on her lap. The temperature underneath registered 51 degrees.
That case, from 2007, is one of 10 laptop-related cases reported in medical journals in the past six years.
Erythema ab igne, also known as hot water bottle rash, fire stains, laptop thigh, and toasted skin syndrome, is caused by long-term exposure to low-level heat. And, in very rare cases, it can cause skin damage that could result in skin cancer.
The image used in the graphic is featured in a Doctorshangout.com article about Erythema ab igne. The case depicted, which appears to be a quite severe example, was reportedly caused by a heating pad applied for joint pain rather than a laptop.
I could find no information documenting skin cancer cases specifically related to laptop use. And, according to the Sydney Morning Herald, Dr Anthony Mancini, dermatology chief at Children’s Memorial Hospital in Chicago notes “it was unlikely that computer use would lead to cancer since it was so easy to avoid prolonged close skin contact with laptops”.
Nevertheless, laptop use can indeed cause toasted skin syndrome as claimed and if you habitually use a laptop across your legs for prolonged periods, it might be wise to take heed of this warning.