Interobserver Agreement on Dermoscopic Features and their Associations with In Situ and Invasive Cutaneous Melanomas
Sam Polesie, Lisa Sundback, Martin Gillstedt, Hannah Ceder, Johan Dahlén Gyllencreutz, Julia Fougelberg, Eva Johansson Backman, Jenna Pakka, Oscar Zaar, John Paoli
Several melanoma-specific dermoscopic features have been described, some of which have been reported as indicative of in situ or invasive melanomas. To assess the usefulness of these features to differentiate between these 2 categories, a retrospective, single-centre investigation was conducted. Dermoscopic images of melanomas were reviewed by 7 independent dermatologists. Fleiss’ kappa (κ) was used to analyse interobserver agreement of predefined features. Logistic regression and odds ratios were used to assess whether specific features correlated with melanoma in situ or invasive melanoma. Overall, 182 melanomas (101 melanoma in situ and 81 invasive melanomas) were included. The interobserver agreement for melanoma-specific features ranged from slight to substantial. Atypical blue-white structures (κ=0.62, 95% confidence interval 0.59–0.65) and shiny white lines (κ=0.61, 95% confidence interval 0.58–0.64) had a substantial interobserver agreement. These 2 features were also indicative of invasive melanomas >1.0 mm in Breslow thickness. Furthermore, regression/peppering correlated with thin invasive melanomas. The overall agreement for classification of the lesions as invasive or melanoma in situ was moderate (κ=0.52, 95% confidence interval 0.49–0.56).
Dermoscopy improves dermatologists’ assessment of skin tumours, including melanoma. Specific dermoscopic features that may guide dermatologists in deciding whether a melanoma is thick or thin have been proposed, but little is known about how well dermatologists agree on their presence (or absence) in a preoperative setting, which must be considered instrumental for their clinical transferability. This study highlights that 2 specific features, shiny white lines and atypical blue-white structures, both display moderate to substantial between dermatologists and are suggestive of thicker melanomas, while regression/peppering are more indicative of thinner lesions. Overall agreement between dermatologists in classifying lesions as invasive or in situ was moderate.