March 31 (HealthDay News) -- Identifying the differences between melanoma skin cancer and a harmless mole can still be a tough call for even trained specialists. But scientists say differences in levels of certain genetic markers may help distinguish between the two lesions.

Melanoma is the deadliest form of skin cancer. Standard microscopic examinations of tissue biopsies can be ambiguous, so using this new technique along with standard practice could help clarify difficult-to-diagnosis cases, according to researchers from the University of California, San Francisco.

They found that both the level and the pattern of activity of five proteins can distinguish benign moles from melanoma. Testing the diagnostic technique on 693 previously diagnosed tissue samples, they found that it correctly diagnosed 91 percent of melanomas and 95 percent of benign moles. The technique also correctly diagnosed 75 percent of the most difficult cases that had previously been misdiagnosed.

"We have a test that can help patients and help clinicians who treat melanoma. With this added diagnostic tool, we can shed light on lesions that are difficult to classify and diagnose," lead author Dr. Mohammed Kashani-Sabet, professor of dermatology at UCSF and director of the Melanoma Center at the UCSF Helen Diller Family Comprehensive Cancer Center, said in a university news release.

The study was published online and will appear in a future print issue of the journal Proceedings of the National Academy of Sciences.

The UCSF study is the first to demonstrate both the diagnostic accuracy and practicality of a multi-biomarker approach to diagnosing melanoma, which can spread to almost any organ in the body and is difficult to treat in its advanced stages, the researchers said. Early diagnosis is crucial to improving the chances of survival.

SOURCE: University of California, San Francisco, news release, March 30, 2009