Last year, doctors told 1.3 million patients in the United States that they had skin cancer. But still more people underwent painful biopsies-in which a suspect mole is cut off, sliced into thin sections and examined under a microscope-on what turned out to be healthy skin. A new laser-based imaging device could allow doctors to peer painlessly into the skin and diagnose growths without surgical biopsies.

The device is a descendant of a laboratory tool called the confocal microscope. By scanning a laser beam across a tissue sample and detecting the light reflected back, the desk-sized microscope can piece together highly detailed images of successive layers of cells, creating virtual slices through the tissue. Lucid in Rochester, NY, and Optiscan Imaging in Notting Hill, Australia, are adapting the microscope to the doctor's office. Ashfaq Marghoob, a dermatologist at Memorial Sloan-Kettering Cancer Center in New York who is testing Lucid's "VivaScope," is enthusiastic about the technology. "Instead of cutting out hundreds of moles, you can just scan them and follow any changes over time," Marghoob says.

Preliminary studies indicate that devices like the VivaScope and Optiscan's Stratum may be as reliable as standard biopsies in diagnosing many forms of skin cancer. Lucid senior vice president Stuart Itkin says the company aims to have a commercial model ready by May; Optiscan is planning to begin U.S. clinical trials around January. Itkin says confocal microscopy could be used to detect other cancers as well, replacing Pap smears and cervix and mouth biopsies.

Getting doctors to accept the new tool will be key to realizing that vision, though. That's why Harvard Medical School pathologist Martin Mihm, a consultant for Lucid, is developing software to make the microscope's images look more like biopsy slides. "If it's not familiar to pathologists, [it's] more difficult to use," Mihm says. But if the device developers can make the diagnostic tool simple and accurate enough, millions of anxious patients will have one less thing to fear.