Dermatoscopy of combined blue nevi: a multicentre study of the International Dermoscopy Society

Abstract

Background Combined blue nevi (CBN) may mimic melanoma and are relatively often biopsied for diagnostic reasons. Objective To better characterize CBN and to compare it with melanoma. Methods We collected clinical and dermatoscopic images of 111 histologically confirmed CBN and contrasted their dermatoscopic characteristics with 132 partly blue coloured melanomas. Furthermore, we compared the accuracy of human experts using pattern analysis with a computer algorithm based on deep learning. Results Combined blue nevi are usually flat or slightly elevated and, in comparison with melanoma, more frequent on the head and neck. Dermatoscopically, they are typified by a blue structureless part in combination with either brown clods (n = 52, 46.8%), lines (n = 28, 25.2%) or skin‐coloured or brown structureless areas (n = 31, 27.9%). In contrast with melanoma, the blue part of CBN is more often well defined (18.9% vs. 4.5%, P < 0.001) and more often located in the centre (22.5% vs. 5.3%, P < 0.001). Melanomas are more often chaotic (OR: 28.7, 95% CI: 14.8–55.7, P < 0.001), have at least one melanoma clue (OR: 10.8, 95% CI: 5.2–22.2 P < 0.001) in particular white lines (OR: 37.1, 95% CI: 13.4–102.9, P < 0.001). Using simplified pattern analysis (chaos and clues), two raters reached sensitivities of 93.9% (95% CI: 88.4–97.3%) and 92.4% (95% CI: 86.5–96.3%) at corresponding specificities of 59.5% (95% CI: 49.7–68.7%) and 65.8% (95% CI: 56.2–74.5%). The human accuracy with pattern analysis was on par with a state‐of‐the‐art computer algorithm based on deep learning that achieved an area under the curve of (0.92, 95% CI: 0.87–0.96) and a specificity of 85.3% (95% CI: 76.5–91.7%) at a given sensitivity of 83.6% (95% CI: 72.5–91.5%). Conclusion CBN usually lack melanoma clues, in particular white lines. The accuracy of pattern analysis for combined nevi is acceptable, and histopathologic confirmation may not be necessary in exemplary cases.

Lesion- and Patient-Related Variables May Provide Additional Clues during Dermoscopic Assessment of Blue Nevi—A Retrospective Cohort Study

“…Combined BN are formed by two populations of melanocytes and dermoscopically often present with a combination of blue/brown colors. In a recent study by IDS, mainly including flat or slightly elevated lesions located on the trunk or head and neck [3], predominant dermoscopic patterns of such a type of BN were structureless blue in combination with brown clods, lines, or skin-colored/brown structureless areas. In comparison to analyzed melanoma instances, the blue part of combined BN was more often well-defined and located in the center of the lesion.…”

“…Due to the wide clinical and dermoscopic presentation, their diagnosis may sometimes be difficult, especially if the history of lesion occurrence is unknown. Although BN are not particularly rare, few studies concerning their dermoscopic features have been published [1][2][3]. Additionally, the literature data is even more limited when it comes to the association of specific dermoscopic features of BN and clinical variables, with only one study investigating the possible influence of age and anatomical localization of the lesions [2].…”

Dermoscopy of haemosiderotic/aneurysmal dermatofibroma: A morphological study of 110 cases

“…This pattern was previously reported by Zaballos et al in their series of 412 dermatofibromas and was histologically associated with HADFs 21 . Some melanocytic tumours, such as invasive melanomas, combined blue nevi or Spitz nevi can rarely display a similar pattern 36,37 . However, it should be noted that the pigment network of melanocytic neoplasms differs from the PDN of HADFs in terms of line thickness, homogeneity and distribution 23 .…”

“…21 Some melanocytic tumours, such as invasive melanomas, combined blue nevi or Spitz nevi can rarely display a similar pattern. 36,37 However, it should be noted that the pigment network of melanocytic neoplasms differs from the PDN of HADFs in terms of line thickness, homogeneity and distribution. 23 On this basis, the presence of a PDN may be considered a useful dermoscopic clue for the differential diagnosis with other skin neoplasms, mainly with melanomas.…”

Recent Advances in Diagnosis of Skin Lesions Using Dermoscopic Images Based on Deep Learning

“…Because of the similarity in color, texture, edge contour, and other features between different skin lesions, and the difference in pathological tissues between different patients, it is a big challenge to classify skin cancer. Deep convolutional neural networks have been used for general and highly variable tasks across many studies [117], [139], [140], [143]- [150].…”