Dermoscopy of Melanoma and Naevi
Dermoscopy has been proven to increase the observer's diagnostic accuracy for skin lesions. It has also increased the sensitivity and specificity for the diagnosis of skin cancer, in particular melanoma, allowing for the detection of more melanomas at an early stage. While naevi usually display a symmetrical and organized dermoscopic pattern, melanomas usually manifest an asymmetrical, disorganized and chaotic pattern. Most melanomas will reveal at least one melanoma‐specific structure (i.e. atypical network, negative network, streaks, crystalline structures, atypical dots/globules, irregular blotch, blue‐white veil, regression structures, atypical vessels, peripheral tan structureless areas). Besides the aforementioned melanoma‐specific structures, melanomas located on the face, chronic sun‐damaged skin, volar skin, nails and mucosae often display other dermoscopic structures of concern such as the annular–granular pattern, polygonal lines, parallel ridge pattern and disruption in parallelism, just to mention a few. This chapter provides an overview of the dermosocopic evaluation of naevi, in particular those naevi that are frequently subjected to biopsy to rule out melanoma, and outlines the dermoscopic features of melanoma, according to their histological subtype and anatomical location.
Keywords dermoscopy, melanoma, naevi, lentigo maligna, nail melanoma, acral melanoma, mucosal melanoma, desmoplastic melanoma, nodular melanoma, amelanotic melanoma