Dermoscopic patterns of intradermal naevi

Background: Intradermal naevi represent a benign histopathological variant of common melanocytic naevi. Studies describing dermoscopic criteria of dermal naevi are very limited. Objectives: To identify dermoscopic features of dermal naevi in order to facilitate differential diagnosis from malignant lesions. Methods: A 15-year retrospective study was performed to evaluate the dermoscopic characteristics of 202 dermal naevi, histopathologically diagnosed through the analysis of digital dermoscopic images performed with polarised light dermoscopy. For each lesion, vascular pattern, pigment pattern and other dermoscopic clues were evaluated. Results: 147 Unna naevi and 55 Miescher naevi were included in the study. Brown pigment (37.1%) was the pigment pattern most frequently observed in both Unna and Miescher naevi, followed by cobblestone pattern (30.6%) in Unna naevi and white areas (23.6%) and dotted/globule pattern (20%) in Miescher naevi. As regards the vascular patterns, the polymorphic one was the most frequently observed (34.6%). The combination between comma-shaped and arborising vessels was the most common among all naevi. Conclusions: Our study describes the dermoscopic features of dermal naevi that may help to differentiate them from malignant lesions such as basal cell carcinoma, amelanotic melanoma and Spitz naevi.