The device shoots a double laser beam into a potentially malignant mole and analyzes its pigments. Higher concentrations of the black pigment eumelanin can indicate cancer.
The team accurately identified all 11 samples with melanoma.
Even if only 50 percent successful, the procedure could prevent hundreds of thousands of false diagnoses, researcher Thomas Matthews said in the study, published in Science Translational Medicine. The research was reported in The Daily Telegraph of London.
The Duke team now plans to use the laser on thousands of archived skin slices.
The current method for studying a mole or performing a tissue biopsy is to use a light and magnifying glass.
Warren Warren, head of Duke's Center for Molecular and Biomolecular Imaging, said the first method was a "17th-century technique that is only 85 percent reliable."
Doctors also disagree on whether cells are cancerous in 14 percent of biopsies, he said.
With the new technique, a suspicious mole would still have to be removed for a final diagnosis.