Smartphone applications used to assess photos of skin lesions classified at least 30 per cent of melanomas incorrectly as benign, say doctors who warn against using the apps.

Researchers tested four smartphone apps to evaluate images of skin lesions. The products are marketed as educational rather than medical devices.

Relying on melanoma apps without consulting a doctor can delay diagnosis, says Dr. Laura Ferris. (Ronald A. Fontana/University of Pittsburgh/Canadian Press)

Principal author Dr. Laura Ferris, a dermatologist at the University of Pittsburgh Medical Center, and her co-authors sent 188 images of lesions to be evaluated by the apps, which were not identified by name.

"The performance of smartphone applications in assessing melanoma risk is highly variable, and three of four smartphone applications incorrectly classified 30 per cent or more of melanomas as unconcerning," the study's authors concluded.

"Reliance on these applications, which are not subject to regulatory oversight, in lieu of medical consultation can delay the diagnosis of melanoma and harm users."

Melanoma is the most dangerous type of skin cancer. It often starts out as a coloured mole or spot, but can spread quickly to surrounding skin and other organs.

In the study, the researchers used photographs of lesions that had been removed or biopsied and tested by a pathologist.

Only close-up images with a clear diagnosis from a board-certified dermatologist — 60 melonomas and 128 benign — were used.

A melanoma that was misdiagnosed as a benign lesion by three out of four smart phone apps. (University of Pittsburgh Department of Dermatology/Canadian Press)

Three of the apps, which cost less than $5, gave answers immediately, and the fourth took about 24 hours for a dermatologist to analyze. That app charged $5 per lesion.

Unlike the other, the performance of the dermatologist app was 98 per cent.

Dr. Michael Sabel, an oncologist who specializes in melanoma, said his team at the University of Michigan decided against having people send photographs to them to make a diagnosis.

Instead, the UMSkinCheck, asks users to upload photographs of various parts of the body and sends a reminder to take a new set of photos regularly to compare over time.

"This should be a tool to be used in concert," with health-care professionals, Sabel said of UMSkinCheck.

The study was funded by the U.S. National Institutes of Health.

With files from the Canadian Press