Many dermatologists worry about missing melanomas, and in 2011 the FDA approved a tool that could help them catch more of these aggressive skin cancers. But the word is still out on whether it works. Called MelaFind, the device can 'see' 2.5 mm deep into the skin, makes images of different layers, and uses pattern-recognition algorithms to assess the likelihood of melanoma. Drawbacks include that MelaFind can only be used on small pigmented spots and that it gives a lot of false positives, which could lead to unnecessary biopsies. But dermatologists who use this tool say that they use their own judgment to make the final call and that MelaFind makes them more confident in their diagnoses.