Melanomas may be distinguishable visually from benign irregular skin moles when all of a patient's irregular moles are evaluated at the same time, according to an article in the January issue of Archives of Dermatology.

Rates of malignant melanoma continue to increase, and early identification allows surgeons to treat the disease by removing the tumor, according to background information in the article. The disease is more common in individuals with many moles or other skin marks, especially if the marks are atypical in color, shape or size.

"The challenge for clinicians who diagnose and treat pigmented skin lesions is to distinguish between malignant melanoma and benign simulants," the authors wrote.

Alon Scope, MD, of the Memorial Sloan-Kettering Cancer Center, New York, and colleagues obtained images of the backs of 12 patients from a database of standardized patient images. All of the patients had at least 8 atypical moles, and 5 patients had 1 lesion that had been confirmed as a melanoma.

A total of 34 participants-including 8 pigmented lesion experts, 13 general dermatologists, 5 dermatology nurses, and 8 nonclinical medical staff-were asked to evaluate the images and identify lesions that looked different from all other atypical moles.

All 5 melanomas and only 3 of 140 benign lesions (2.1 percent) were generally apparent as different, meaning that two-thirds of the participants identified them as distinct in appearance.

"The malignant melanomas were apparent as being different to at least 85 percent of participants, whereas the agreement rate on the benign lesions perceived as being different was 76 percent at most," the authors wrote. "Four lesions were generally apparent as completely different, all four being malignant melanomas."

For all participants, the test had a sensitivity of 90 percent, meaning 90 percent of the melanomas were identified as different. Sensitivity was 100 percent for the pigmented lesion experts, 89 percent for general dermatologists, 88 percent for nurses and 85 percent for nonclinicians.

"Although the sensitivity and specificity and diagnostic accuracy of the ugly duckling sign depended on clinical expertise, the values for these parameters were good in all subgroups of participants," the authors concluded. "These preliminary findings suggest that the ugly duckling sign may prove to be a useful screening strategy for primary health care providers and even for skin self-examination."