Identification of clinically featureless incipient melanoma using sequential dermoscopy imaging

Objectives: To examine the role of sequential dermoscopy imaging in detecting incipient melanoma and to elucidate the impact of length of follow-up on the relevance of observed changes. Design: Baseline and follow-up images of melanomas and melanocytic nevi excised only because of changes across time were inspected on a computer screen and assessed according to prospectively defined criteria. Lesions were stratified into 3 groups according to the length of follow-up. Setting: Three hospital-based referral centers in Europe and Australia. Patients: Four hundred sixty-one patients selected for digital dermoscopy monitoring. Main Outcome Measures: Description and comparison of dermoscopy features and changes in melanomas and melanocytic nevi at baseline and after follow-up. Results: We inspected baseline and follow-up images of 499 melanocytic skin lesions from 461 patients. The histopathologic diagnosis was melanoma in 91 cases and melanocytic nevus in 408. Most melanomas (58.2%; n = 53) were in situ, and the median thickness of invasive melanomas was 0.38 mm. Dermoscopy features of melanomas and nevi did not differ significantly at baseline. After follow-up of 1.5 to 4.5 months, 61.8% of the melanomas showed no specific dermoscopy features for melanoma. This value declined to 45.0% after follow-up of 4.5 to 8.0 months and to 35.1% after more than 8.0 months. We could not differentiate melanomas and changing nevi by means of observed changes or dermoscopy features when follow-up was shorter than 4.5 months. With longer follow-up, melanomas tended to enlarge asymmetrically with architectural and color changes, and nevi tended to enlarge symmetrically without architectural and color changes. Conclusions: Sequential dermoscopy imaging detects incipient melanomas when they are still featureless. Interpretation of changes observed during follow-up depends on the length of follow-up.