Use of Ugly Duckling Sign Could Improve Efficiency of Melanoma Detection

The identification of ugly duckling nevi (UDN), a term used to describe a nevus that is obviously different from others on an individual, using a whole-body skin examination for intrapatient comparative analysis (IPCA) is a reliable cognitive process, according to the results of a study published in JAMA Dermatology.

In other words, when a group of expert dermatologists had access to all nevi on a given patient, they were able to decrease the number of nevi biopsied and the number needed to treat for one melanoma compared with the use of a separate analysis of each individual nevus.

“This study demonstrated that dermatologists who cannot access the patient’s entire skin and perform IPCA will not be as effective as they can be; thus, examining only a nevus that concerns the patient, examining a patient who is not undressed, or assessing only the images of suspicious lesions that were transmitted electronically will not achieve the greatest accuracy,” wrote researcher Caroline Gaudy-Marqueste, MD, PhD, of the dermatology and skin cancer department at Hôpital Timone in Marseille, France, and colleagues. “Promoting the use of IPCA in the diagnosis of melanoma may improve early detection.”

For the study, 9 dermatologists were presented with the same 2,089 digital images of the nevi of a sample of 80 patients and 766 dermoscopic images from a subset of 30 patients; all melanoma were labeled as UDN and as morphologically suspicious nevi by all 9 dermatologists. These images were presented in two experiments designed to reproduce a whole-body skin examination (IPCA) and a morphologic analysis (lesion-focused analysis [LFA]).

The median number of UDN detected per patient was 0.8 among clinical images and 1.26 among the dermoscopic images.

The dermatologists’ propensity to consider more or less of the nevi as UDN was independent of the presentation as a clinical or dermoscopic image. However, agreement among the experts regarding UDN was lower with the dermoscopic images than it was for the clinical images.

When both IPCA and LFA were used, the number of nevi considered for biopsy was reduced by a factor of 6.9 compared with LFA alone.

“Including the concept of IPCA using the ugly duckling sign in the education of medical students, the training of practicing physicians, and campaigns targeted to the community could probably improve the accuracy of diagnosis of melanoma,” the researchers wrote. “Moreover, our data are important in computer-assisted diagnosis systems and telemedicine, which may have improved accuracy with the use of IPCA.”