New smart phone apps now let you snap a picture and upload it for a skin cancer check. Sure sounds a lot easier than trekking into the dermatologist, right? But a new review of these apps finds that most of them are not very accurate.

Dermatologists uploaded 188 images of skin lesions to four different app-based services. The apps, which are unregulated, mostly use algorithms to judge—often in less than a minute—whether the spot is benign or something to get checked out. Three of the four apps failed to catch at least one-in-three known cases of melanoma. The apps also falsely identified plenty of benign growths as possibly cancerous. The findings are in the journal JAMA Dermatology. [Joel Wolf et al., Diagnostic Inaccuracy of Smartphone Applications for Melanoma Detection]

The fourth app, which did okay, actually used board-certified dermatologists to review images. It was the most expensive at five bucks per assessment and took 24 hours.

So next time you're worried about a mole, don’t use an app, get an ap—pointment…with a dermatologist.

—Katherine Harmon

[The above text is a transcript of this podcast.]