Multi-marker test helps diagnose melanoma

NEW YORK (Reuters Health) - A test that looks for five genes overexpressed in melanomas can help distinguish these tumors from benign nevi, according to a report in the March 30th Early Edition of the Proceedings of the National Academy of Sciences.

The histopathologic diagnosis of the malignant melanoma can be difficult, Dr. Mohammed Kashani-Sabet, from the University of California, San Francisco, and colleagues note. At present, there are no molecular markers in use to differentiate melanoma from nevi.

In the current study, the authors tested an assay that measures expression of ARPC2, FN1, RGS1, SPP1, and WNT2, all of which have been shown to be overexpressed in melanoma. The test was first applied to 693 melanocytic neoplasms and then evaluated in four independent validation sets: tissue samples of 38 melanomas within a nevus, 39 dysplastic nevi, 21 Spitz nevi, and 24 misdiagnosed melanocytic neoplasms.

Based on the initial test results, the authors created a diagnostic algorithm that was highly accurate in distinguishing melanoma from nevi. By assessing both the intensity and pattern of gene expression, the test was able to detect malignant disease with 91% sensitivity and 95% specificity in the training set.

The assay also performed well in the validation sets, correctly identifying 97% of melanomas arising in a nevus; 95% of dysplastic nevi sections; and 95% of Spitz nevi. The assay also correctly diagnosed 75% of the misdiagnosed melanocytic neoplasms.

"The multi-marker assay described here," the authors conclude, "could be used to assist in the histologic diagnosis of melanoma, thereby providing important information to pathologists and other clinicians responsible for caring for patients with melanocytic neoplasms that are difficult to classify."

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