Objective: To compare dermoscopic features of melanocytic nevi with those of early melanomas that were not excised initially because of their uncharacteristic clinical and dermoscopic appearance.
Design: Retrospective study of the baseline images of 325 melanocytic skin lesions that were observed by digital dermoscopy and finally excised because of changes over time.
Setting: A dermatologic clinic and a dermatologic department at a university hospital.
Main outcome measures: Comparison of baseline images of melanomas and melanocytic nevi by pattern analysis, the ABCD rule of dermoscopy, and the 7-point checklist.
Results: Baseline dermoscopic images of 262 melanocytic nevi and 63 melanomas from 315 patients were included in the analysis. The patterns of dermoscopic features observed in the baseline images of melanocytic lesions finally diagnosed as melanomas during follow-up did not differ substantially from the patterns observed in the baseline images of melanocytic nevi. Pattern analysis, the ABCD rule of dermoscopy, and the 7-point checklist failed to achieve adequate diagnostic accuracy for melanoma. In retrospect, no dermoscopic feature or pattern of features could be identified that reliably differentiated between melanomas and melanocytic nevi at the time of the first presentation.
Conclusion: Dermoscopy depends on the appearance of classic dermoscopic features and is therefore limited in the diagnosis of very early and mainly featureless melanomas.