Validity of ABCD Rule of Dermoscopy in Clinical Practice.

The ABCD rule of dermoscopy was developed to facilitate the dermoscopic differentiation between benign and malignant melanocytic lesions. However, there is a lack of studies on its validity in clinical practice. The aim of this study was to evaluate the accuracy of the algorithm used bedside, compared with the accuracy of the preliminary preoperative diagnosis, and to rate physicians' level of confidence in the diagnosis. Melanocytic tumours were preoperatively scored bedside, according to the ABCD algorithm; 309 cases (46 melanomas and 263 naevi) were included. A sensitivity of 83% and specificity of 45% were found for the ABCD algorithm. A comparable sensitivity (74%), but a significantly higher specificity (91%), was found for the preliminary diagnosis. Interestingly, there was a considerable percentage (19.6%) of early melanomas for which a malignant diagnosis was not preoperatively expected, indicating that it is important to maintain generous indications for excision or to practise short-term follow-up of ambiguous lesions in order to detect early melanomas.