Larger Skin Lesions More Likely Melanoma

(Ivanhoe Newswire) -- Larger skin lesions are more likely to be melanomas -- the deadliest form of skin cancer.

A new report from the New York University School of Medicine finds skin lesions larger than six millimeters in diameter seem more likely to be melanomas than smaller ones. This suggests the diameter guidelines dermatologists use to screen patients work.

Many physicians use the ABCDE method to screen for melanoma. They look for various characteristics of the skin cancer that start with these letters -- Asymmetry, Border irregularity, Color variation, Diameter larger than six millimeters, and Evolution or changes in the lesion. But some critics argued sticking to the diameter guideline will cause doctors to miss smaller melanomas.

Researchers looked at 1,323 patients having biopsies of 1,657 skin lesions. They found 48.5 percent of the lesions were larger than six millimeters in diameter and 8.3 percent were diagnosed as melanoma. Invasive melanoma, which has grown deeper into the skin, was diagnosed in 1.5 percent of lesions that were six millimeters or smaller and in 5.1 percent of those larger than six millimeters. In situ melanomas -- the ones on the skin’s outer layers -- were diagnosed in 2.6 percent of lesions six millimeters or smaller and in 7.7 percent of those larger than six millimeters.

The proportion of melanomas did not vary much in those between 2.01 and six millimeters. But there was a nearly 100 percent increase in the proportion of melanomas between the 5.01 to six millimeter category (4.3 percent) to the 6.01 to seven millimeter category (8.3 percent).

The authors recommend keeping the diameter criterion of larger than six millimeters as part of the ABCDE screening and do not recommend changing the "D" criterion at this time.

Sign up for a free weekly e-mail on Medical Breakthroughs called First to Know by clicking here.

SOURCE: Archives of Dermatology, 2008;144:469-474