Boder irregularity : atypical moles versus melanoma

Malignant melanomas are often difficult to differentiate from atypical moles. There are, however, some features such as the ABCD (asymmetry, border irregularity, color variability, diameter > 6 mm) characteristics that may assist in making the diagnosis. This study attempts to quantify border irregularity, one of these characteristics. Seventy-two melanocytic neoplasms, each either an atypical mole suspicious for malignant melanoma or an early malignant melanoma, were photographed with oil (dermoscopic photo) and without oil (clinical or conventional photo) at the same magnication. The 35 mm transparencies were visualized at 20 X magnification on a rear-view projector and the outlines of the images traced onto transparent plastic sheets from which they were transferred into the Global Lab Images® computer program. Area, perimeter, and border irregularity index were calculated by the computer for each image. Histologically, 21 lesions were malignant melanomas and 51 atypical moles. The malignant melanomas had a significantly higher mean border irregularity index than the atypical moles, as determined on both the clinical and the dermoscopic images. There were also significant differences in the mean border irregularity indices between the clinical images and the dermoscopic images for each type of lesion. Border irregularity of melanocytic neoplasms may be helpful in differentiating melanomas from atypical moles. Borders of melanomas are significantly more irregular than atypical moles. It seems that for both melanomas and atypical moles the irregularity of the edges is better appreciated with dermoscopy than with ordinary clinical examination.