The study was approved by the local ethics committee and performed in accordance with the Declaration of Helsinki. Initially, 69 patients were recruited from the University Hospital, Gothenburg, Sweden, of which 60 lesions were included in the study. The inclusion criteria were lesions clinically suspicious for melanoma and showing positive SIAscopic findings. Thirty out of the 60 lesions were processed in total accordance to the protocol, as described in the following paragraphs. Of these 30 lesions, 19 were invasive melanomas (66% of the total number of invasive melanomas), seven melanoma in situ (54% of the total number melanoma in situ) and four benign nevi (22% of the total number of benign nevi). Nine lesions (2 invasive melanoma, two melanoma in situ, and five benign lesions) had to be excluded due to technical problems. Due to stepwise development of the histopathological procedure, precise adherence to all details in the study protocol did not occur for the first 30 lesions. In 25 lesions deviating from the protocol, images or detailed drawings of the sectioned specimens were available, enabling localization of the SIAscopic areas of interest. In five lesions, only schematic drawings of the specimens were available, which could not be used for precise orientation; however, areas of interest indicated by SIAscopy were very large in these lesions and thereby still possible to identify. Remaining uncertainties were eliminated by step-sectioning the tissue slices as described below. There is thus no doubt that the areas of interest were properly scrutinized, and the deviations from protocol deemed not to significantly impair the validity of the observations made.